detach()
If self is alive then mark it as dead and return the tuple (obj, func, args, kwargs). If self is dead then return None.


peek()
If self is alive then return the tuple (obj, func, args,
kwargs). If self is dead then return None.


__call__()
If self is alive then mark it as dead and return the result of calling func(*args, **kwargs). If self is dead then return None.


weakref.getweakrefcount(object)
Return the number of weak references and proxies which refer to object.


weakref.getweakrefs(object)
Return a list of all weak reference and proxy objects which refer to object.


weakref.proxy(object[, callback])
Return a proxy to object which uses a weak reference. This supports use of the proxy in most contexts instead of requiring the explicit dereferencing used with weak reference objects. The returned object will have a type of either ProxyType or CallableProxyType, depending on whether object is callable. Proxy objects are not hashable regardless of the referent; this avoids a number of problems related to their fundamentally mutable nature, and prevent their use as dictionary keys. callback is the same as the parameter of the same name to the ref() function.  Changed in version 3.8: Extended the operator support on proxy objects to include the matrix multiplication operators @ and @=.


weakref.ProxyType
The type object for proxies of objects which are not callable.


weakref.ProxyTypes
Sequence containing all the type objects for proxies. This can make it simpler to test if an object is a proxy without being dependent on naming both proxy types.


class weakref.ref(object[, callback])
Return a weak reference to object. The original object can be retrieved by calling the reference object if the referent is still alive; if the referent is no longer alive, calling the reference object will cause None to be returned. If callback is provided and not None, and the returned weakref object is still alive, the callback will be called when the object is about to be finalized; the weak reference object will be passed as the only parameter to the callback; the referent will no longer be available. It is allowable for many weak references to be constructed for the same object. Callbacks registered for each weak reference will be called from the most recently registered callback to the oldest registered callback. Exceptions raised by the callback will be noted on the standard error output, but cannot be propagated; they are handled in exactly the same way as exceptions raised from an object’s __del__() method. Weak references are hashable if the object is hashable. They will maintain their hash value even after the object was deleted. If hash() is called the first time only after the object was deleted, the call will raise TypeError. Weak references support tests for equality, but not ordering. If the referents are still alive, two references have the same equality relationship as their referents (regardless of the callback). If either referent has been deleted, the references are equal only if the reference objects are the same object. This is a subclassable type rather than a factory function.
__callback__
This read-only attribute returns the callback currently associated to the weakref. If there is no callback or if the referent of the weakref is no longer alive then this attribute will have value None.
  Changed in version 3.4: Added the __callback__ attribute.


__callback__
This read-only attribute returns the callback currently associated to the weakref. If there is no callback or if the referent of the weakref is no longer alive then this attribute will have value None.


weakref.ReferenceType
The type object for weak references objects.


class weakref.WeakKeyDictionary([dict])
Mapping class that references keys weakly. Entries in the dictionary will be discarded when there is no longer a strong reference to the key. This can be used to associate additional data with an object owned by other parts of an application without adding attributes to those objects. This can be especially useful with objects that override attribute accesses.  Changed in version 3.9: Added support for | and |= operators, specified in PEP 584.


WeakKeyDictionary.keyrefs()
Return an iterable of the weak references to the keys.


class weakref.WeakMethod(method)
A custom ref subclass which simulates a weak reference to a bound method (i.e., a method defined on a class and looked up on an instance). Since a bound method is ephemeral, a standard weak reference cannot keep hold of it. WeakMethod has special code to recreate the bound method until either the object or the original function dies: >>> class C:
...     def method(self):
...         print("method called!")
...
>>> c = C()
>>> r = weakref.ref(c.method)
>>> r()
>>> r = weakref.WeakMethod(c.method)
>>> r()
<bound method C.method of <__main__.C object at 0x7fc859830220>>
>>> r()()
method called!
>>> del c
>>> gc.collect()
0
>>> r()
>>>
  New in version 3.4.


class weakref.WeakSet([elements])
Set class that keeps weak references to its elements. An element will be discarded when no strong reference to it exists any more.


class weakref.WeakValueDictionary([dict])
Mapping class that references values weakly. Entries in the dictionary will be discarded when no strong reference to the value exists any more.  Changed in version 3.9: Added support for | and |= operators, as specified in PEP 584.


WeakValueDictionary.valuerefs()
Return an iterable of the weak references to the values.


webbrowser — Convenient Web-browser controller Source code: Lib/webbrowser.py The webbrowser module provides a high-level interface to allow displaying Web-based documents to users. Under most circumstances, simply calling the open() function from this module will do the right thing. Under Unix, graphical browsers are preferred under X11, but text-mode browsers will be used if graphical browsers are not available or an X11 display isn’t available. If text-mode browsers are used, the calling process will block until the user exits the browser. If the environment variable BROWSER exists, it is interpreted as the os.pathsep-separated list of browsers to try ahead of the platform defaults. When the value of a list part contains the string %s, then it is interpreted as a literal browser command line to be used with the argument URL substituted for %s; if the part does not contain %s, it is simply interpreted as the name of the browser to launch. 1 For non-Unix platforms, or when a remote browser is available on Unix, the controlling process will not wait for the user to finish with the browser, but allow the remote browser to maintain its own windows on the display. If remote browsers are not available on Unix, the controlling process will launch a new browser and wait. The script webbrowser can be used as a command-line interface for the module. It accepts a URL as the argument. It accepts the following optional parameters: -n opens the URL in a new browser window, if possible; -t opens the URL in a new browser page (“tab”). The options are, naturally, mutually exclusive. Usage example: python -m webbrowser -t "http://www.python.org"
 The following exception is defined:
exception webbrowser.Error
Exception raised when a browser control error occurs.
 The following functions are defined:
webbrowser.open(url, new=0, autoraise=True)
Display url using the default browser. If new is 0, the url is opened in the same browser window if possible. If new is 1, a new browser window is opened if possible. If new is 2, a new browser page (“tab”) is opened if possible. If autoraise is True, the window is raised if possible (note that under many window managers this will occur regardless of the setting of this variable). Note that on some platforms, trying to open a filename using this function, may work and start the operating system’s associated program. However, this is neither supported nor portable. Raises an auditing event webbrowser.open with argument url.

webbrowser.open_new(url)
Open url in a new window of the default browser, if possible, otherwise, open url in the only browser window.

webbrowser.open_new_tab(url)
Open url in a new page (“tab”) of the default browser, if possible, otherwise equivalent to open_new().

webbrowser.get(using=None)
Return a controller object for the browser type using. If using is None, return a controller for a default browser appropriate to the caller’s environment.

webbrowser.register(name, constructor, instance=None, *, preferred=False)
Register the browser type name. Once a browser type is registered, the get() function can return a controller for that browser type. If instance is not provided, or is None, constructor will be called without parameters to create an instance when needed. If instance is provided, constructor will never be called, and may be None. Setting preferred to True makes this browser a preferred result for a get() call with no argument. Otherwise, this entry point is only useful if you plan to either set the BROWSER variable or call get() with a nonempty argument matching the name of a handler you declare.  Changed in version 3.7: preferred keyword-only parameter was added.
 A number of browser types are predefined. This table gives the type names that may be passed to the get() function and the corresponding instantiations for the controller classes, all defined in this module.
Type Name Class Name Notes
'mozilla' Mozilla('mozilla')
'firefox' Mozilla('mozilla')
'netscape' Mozilla('netscape')
'galeon' Galeon('galeon')
'epiphany' Galeon('epiphany')
'skipstone' BackgroundBrowser('skipstone')
'kfmclient' Konqueror() (1)
'konqueror' Konqueror() (1)
'kfm' Konqueror() (1)
'mosaic' BackgroundBrowser('mosaic')
'opera' Opera()
'grail' Grail()
'links' GenericBrowser('links')
'elinks' Elinks('elinks')
'lynx' GenericBrowser('lynx')
'w3m' GenericBrowser('w3m')
'windows-default' WindowsDefault (2)
'macosx' MacOSX('default') (3)
'safari' MacOSX('safari') (3)
'google-chrome' Chrome('google-chrome')
'chrome' Chrome('chrome')
'chromium' Chromium('chromium')
'chromium-browser' Chromium('chromium-browser')    Notes:  “Konqueror” is the file manager for the KDE desktop environment for Unix, and only makes sense to use if KDE is running. Some way of reliably detecting KDE would be nice; the KDEDIR variable is not sufficient. Note also that the name “kfm” is used even when using the konqueror command with KDE 2 — the implementation selects the best strategy for running Konqueror. Only on Windows platforms. Only on Mac OS X platform.   New in version 3.3: Support for Chrome/Chromium has been added.  Here are some simple examples: url = 'http://docs.python.org/'

# Open URL in a new tab, if a browser window is already open.
webbrowser.open_new_tab(url)

# Open URL in new window, raising the window if possible.
webbrowser.open_new(url)
 Browser Controller Objects Browser controllers provide these methods which parallel three of the module-level convenience functions:
controller.open(url, new=0, autoraise=True)
Display url using the browser handled by this controller. If new is 1, a new browser window is opened if possible. If new is 2, a new browser page (“tab”) is opened if possible.

controller.open_new(url)
Open url in a new window of the browser handled by this controller, if possible, otherwise, open url in the only browser window. Alias open_new().

controller.open_new_tab(url)
Open url in a new page (“tab”) of the browser handled by this controller, if possible, otherwise equivalent to open_new().
 Footnotes
1
Executables named here without a full path will be searched in the directories given in the PATH environment variable.


controller.open(url, new=0, autoraise=True)
Display url using the browser handled by this controller. If new is 1, a new browser window is opened if possible. If new is 2, a new browser page (“tab”) is opened if possible.


controller.open_new(url)
Open url in a new window of the browser handled by this controller, if possible, otherwise, open url in the only browser window. Alias open_new().


controller.open_new_tab(url)
Open url in a new page (“tab”) of the browser handled by this controller, if possible, otherwise equivalent to open_new().


exception webbrowser.Error
Exception raised when a browser control error occurs.


webbrowser.get(using=None)
Return a controller object for the browser type using. If using is None, return a controller for a default browser appropriate to the caller’s environment.


webbrowser.open(url, new=0, autoraise=True)
Display url using the default browser. If new is 0, the url is opened in the same browser window if possible. If new is 1, a new browser window is opened if possible. If new is 2, a new browser page (“tab”) is opened if possible. If autoraise is True, the window is raised if possible (note that under many window managers this will occur regardless of the setting of this variable). Note that on some platforms, trying to open a filename using this function, may work and start the operating system’s associated program. However, this is neither supported nor portable. Raises an auditing event webbrowser.open with argument url.


webbrowser.open_new(url)
Open url in a new window of the default browser, if possible, otherwise, open url in the only browser window.


webbrowser.open_new_tab(url)
Open url in a new page (“tab”) of the default browser, if possible, otherwise equivalent to open_new().


webbrowser.register(name, constructor, instance=None, *, preferred=False)
Register the browser type name. Once a browser type is registered, the get() function can return a controller for that browser type. If instance is not provided, or is None, constructor will be called without parameters to create an instance when needed. If instance is provided, constructor will never be called, and may be None. Setting preferred to True makes this browser a preferred result for a get() call with no argument. Otherwise, this entry point is only useful if you plan to either set the BROWSER variable or call get() with a nonempty argument matching the name of a handler you declare.  Changed in version 3.7: preferred keyword-only parameter was added.


exception WindowsError
Only available on Windows.


winreg — Windows registry access These functions expose the Windows registry API to Python. Instead of using an integer as the registry handle, a handle object is used to ensure that the handles are closed correctly, even if the programmer neglects to explicitly close them.  Changed in version 3.3: Several functions in this module used to raise a WindowsError, which is now an alias of OSError.  Functions This module offers the following functions:
winreg.CloseKey(hkey)
Closes a previously opened registry key. The hkey argument specifies a previously opened key.  Note If hkey is not closed using this method (or via hkey.Close()), it is closed when the hkey object is destroyed by Python.

winreg.ConnectRegistry(computer_name, key)
Establishes a connection to a predefined registry handle on another computer, and returns a handle object. computer_name is the name of the remote computer, of the form r"\\computername". If None, the local computer is used. key is the predefined handle to connect to. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.ConnectRegistry with arguments computer_name, key.  Changed in version 3.3: See above.

winreg.CreateKey(key, sub_key)
Creates or opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the key this method opens or creates. If key is one of the predefined keys, sub_key may be None. In that case, the handle returned is the same key handle passed in to the function. If the key already exists, this function opens the existing key. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.CreateKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  Changed in version 3.3: See above.

winreg.CreateKeyEx(key, sub_key, reserved=0, access=KEY_WRITE)
Creates or opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the key this method opens or creates. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_WRITE. See Access Rights for other allowed values. If key is one of the predefined keys, sub_key may be None. In that case, the handle returned is the same key handle passed in to the function. If the key already exists, this function opens the existing key. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.CreateKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  New in version 3.2.   Changed in version 3.3: See above.

winreg.DeleteKey(key, sub_key)
Deletes the specified key. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that must be a subkey of the key identified by the key parameter. This value must not be None, and the key may not have subkeys. This method can not delete keys with subkeys. If the method succeeds, the entire key, including all of its values, is removed. If the method fails, an OSError exception is raised. Raises an auditing event winreg.DeleteKey with arguments key, sub_key, access.  Changed in version 3.3: See above.

winreg.DeleteKeyEx(key, sub_key, access=KEY_WOW64_64KEY, reserved=0)
Deletes the specified key.  Note The DeleteKeyEx() function is implemented with the RegDeleteKeyEx Windows API function, which is specific to 64-bit versions of Windows. See the RegDeleteKeyEx documentation.  key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that must be a subkey of the key identified by the key parameter. This value must not be None, and the key may not have subkeys. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_WOW64_64KEY. See Access Rights for other allowed values. This method can not delete keys with subkeys. If the method succeeds, the entire key, including all of its values, is removed. If the method fails, an OSError exception is raised. On unsupported Windows versions, NotImplementedError is raised. Raises an auditing event winreg.DeleteKey with arguments key, sub_key, access.  New in version 3.2.   Changed in version 3.3: See above.

winreg.DeleteValue(key, value)
Removes a named value from a registry key. key is an already open key, or one of the predefined HKEY_* constants. value is a string that identifies the value to remove. Raises an auditing event winreg.DeleteValue with arguments key, value.

winreg.EnumKey(key, index)
Enumerates subkeys of an open registry key, returning a string. key is an already open key, or one of the predefined HKEY_* constants. index is an integer that identifies the index of the key to retrieve. The function retrieves the name of one subkey each time it is called. It is typically called repeatedly until an OSError exception is raised, indicating, no more values are available. Raises an auditing event winreg.EnumKey with arguments key, index.  Changed in version 3.3: See above.

winreg.EnumValue(key, index)
Enumerates values of an open registry key, returning a tuple. key is an already open key, or one of the predefined HKEY_* constants. index is an integer that identifies the index of the value to retrieve. The function retrieves the name of one subkey each time it is called. It is typically called repeatedly, until an OSError exception is raised, indicating no more values. The result is a tuple of 3 items:
Index Meaning
0 A string that identifies the value name
1 An object that holds the value data, and whose type depends on the underlying registry type
2 An integer that identifies the type of the value data (see table in docs for SetValueEx())   Raises an auditing event winreg.EnumValue with arguments key, index.  Changed in version 3.3: See above.

winreg.ExpandEnvironmentStrings(str)
Expands environment variable placeholders %NAME% in strings like REG_EXPAND_SZ: >>> ExpandEnvironmentStrings('%windir%')
'C:\\Windows'
 Raises an auditing event winreg.ExpandEnvironmentStrings with argument str.

winreg.FlushKey(key)
Writes all the attributes of a key to the registry. key is an already open key, or one of the predefined HKEY_* constants. It is not necessary to call FlushKey() to change a key. Registry changes are flushed to disk by the registry using its lazy flusher. Registry changes are also flushed to disk at system shutdown. Unlike CloseKey(), the FlushKey() method returns only when all the data has been written to the registry. An application should only call FlushKey() if it requires absolute certainty that registry changes are on disk.  Note If you don’t know whether a FlushKey() call is required, it probably isn’t.

winreg.LoadKey(key, sub_key, file_name)
Creates a subkey under the specified key and stores registration information from a specified file into that subkey. key is a handle returned by ConnectRegistry() or one of the constants HKEY_USERS or HKEY_LOCAL_MACHINE. sub_key is a string that identifies the subkey to load. file_name is the name of the file to load registry data from. This file must have been created with the SaveKey() function. Under the file allocation table (FAT) file system, the filename may not have an extension. A call to LoadKey() fails if the calling process does not have the SE_RESTORE_PRIVILEGE privilege. Note that privileges are different from permissions – see the RegLoadKey documentation for more details. If key is a handle returned by ConnectRegistry(), then the path specified in file_name is relative to the remote computer. Raises an auditing event winreg.LoadKey with arguments key, sub_key, file_name.

winreg.OpenKey(key, sub_key, reserved=0, access=KEY_READ)
winreg.OpenKeyEx(key, sub_key, reserved=0, access=KEY_READ)
Opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that identifies the sub_key to open. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_READ. See Access Rights for other allowed values. The result is a new handle to the specified key. If the function fails, OSError is raised. Raises an auditing event winreg.OpenKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  Changed in version 3.2: Allow the use of named arguments.   Changed in version 3.3: See above.

winreg.QueryInfoKey(key)
Returns information about a key, as a tuple. key is an already open key, or one of the predefined HKEY_* constants. The result is a tuple of 3 items:
Index Meaning
0 An integer giving the number of sub keys this key has.
1 An integer giving the number of values this key has.
2 An integer giving when the key was last modified (if available) as 100’s of nanoseconds since Jan 1, 1601.   Raises an auditing event winreg.QueryInfoKey with argument key.

winreg.QueryValue(key, sub_key)
Retrieves the unnamed value for a key, as a string. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that holds the name of the subkey with which the value is associated. If this parameter is None or empty, the function retrieves the value set by the SetValue() method for the key identified by key. Values in the registry have name, type, and data components. This method retrieves the data for a key’s first value that has a NULL name. But the underlying API call doesn’t return the type, so always use QueryValueEx() if possible. Raises an auditing event winreg.QueryValue with arguments key, sub_key, value_name.

winreg.QueryValueEx(key, value_name)
Retrieves the type and data for a specified value name associated with an open registry key. key is an already open key, or one of the predefined HKEY_* constants. value_name is a string indicating the value to query. The result is a tuple of 2 items:
Index Meaning
0 The value of the registry item.
1 An integer giving the registry type for this value (see table in docs for SetValueEx())   Raises an auditing event winreg.QueryValue with arguments key, sub_key, value_name.

winreg.SaveKey(key, file_name)
Saves the specified key, and all its subkeys to the specified file. key is an already open key, or one of the predefined HKEY_* constants. file_name is the name of the file to save registry data to. This file cannot already exist. If this filename includes an extension, it cannot be used on file allocation table (FAT) file systems by the LoadKey() method. If key represents a key on a remote computer, the path described by file_name is relative to the remote computer. The caller of this method must possess the SeBackupPrivilege security privilege. Note that privileges are different than permissions – see the Conflicts Between User Rights and Permissions documentation for more details. This function passes NULL for security_attributes to the API. Raises an auditing event winreg.SaveKey with arguments key, file_name.

winreg.SetValue(key, sub_key, type, value)
Associates a value with a specified key. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the subkey with which the value is associated. type is an integer that specifies the type of the data. Currently this must be REG_SZ, meaning only strings are supported. Use the SetValueEx() function for support for other data types. value is a string that specifies the new value. If the key specified by the sub_key parameter does not exist, the SetValue function creates it. Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the filenames stored in the configuration registry. This helps the registry perform efficiently. The key identified by the key parameter must have been opened with KEY_SET_VALUE access. Raises an auditing event winreg.SetValue with arguments key, sub_key, type, value.

winreg.SetValueEx(key, value_name, reserved, type, value)
Stores data in the value field of an open registry key. key is an already open key, or one of the predefined HKEY_* constants. value_name is a string that names the subkey with which the value is associated. reserved can be anything – zero is always passed to the API. type is an integer that specifies the type of the data. See Value Types for the available types. value is a string that specifies the new value. This method can also set additional value and type information for the specified key. The key identified by the key parameter must have been opened with KEY_SET_VALUE access. To open the key, use the CreateKey() or OpenKey() methods. Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the filenames stored in the configuration registry. This helps the registry perform efficiently. Raises an auditing event winreg.SetValue with arguments key, sub_key, type, value.

winreg.DisableReflectionKey(key)
Disables registry reflection for 32-bit processes running on a 64-bit operating system. key is an already open key, or one of the predefined HKEY_* constants. Will generally raise NotImplementedError if executed on a 32-bit operating system. If the key is not on the reflection list, the function succeeds but has no effect. Disabling reflection for a key does not affect reflection of any subkeys. Raises an auditing event winreg.DisableReflectionKey with argument key.

winreg.EnableReflectionKey(key)
Restores registry reflection for the specified disabled key. key is an already open key, or one of the predefined HKEY_* constants. Will generally raise NotImplementedError if executed on a 32-bit operating system. Restoring reflection for a key does not affect reflection of any subkeys. Raises an auditing event winreg.EnableReflectionKey with argument key.

winreg.QueryReflectionKey(key)
Determines the reflection state for the specified key. key is an already open key, or one of the predefined HKEY_* constants. Returns True if reflection is disabled. Will generally raise NotImplementedError if executed on a 32-bit operating system. Raises an auditing event winreg.QueryReflectionKey with argument key.
 Constants The following constants are defined for use in many _winreg functions. HKEY_* Constants
winreg.HKEY_CLASSES_ROOT
Registry entries subordinate to this key define types (or classes) of documents and the properties associated with those types. Shell and COM applications use the information stored under this key.

winreg.HKEY_CURRENT_USER
Registry entries subordinate to this key define the preferences of the current user. These preferences include the settings of environment variables, data about program groups, colors, printers, network connections, and application preferences.

winreg.HKEY_LOCAL_MACHINE
Registry entries subordinate to this key define the physical state of the computer, including data about the bus type, system memory, and installed hardware and software.

winreg.HKEY_USERS
Registry entries subordinate to this key define the default user configuration for new users on the local computer and the user configuration for the current user.

winreg.HKEY_PERFORMANCE_DATA
Registry entries subordinate to this key allow you to access performance data. The data is not actually stored in the registry; the registry functions cause the system to collect the data from its source.

winreg.HKEY_CURRENT_CONFIG
Contains information about the current hardware profile of the local computer system.

winreg.HKEY_DYN_DATA
This key is not used in versions of Windows after 98.
 Access Rights For more information, see Registry Key Security and Access.
winreg.KEY_ALL_ACCESS
Combines the STANDARD_RIGHTS_REQUIRED, KEY_QUERY_VALUE, KEY_SET_VALUE, KEY_CREATE_SUB_KEY, KEY_ENUMERATE_SUB_KEYS, KEY_NOTIFY, and KEY_CREATE_LINK access rights.

winreg.KEY_WRITE
Combines the STANDARD_RIGHTS_WRITE, KEY_SET_VALUE, and KEY_CREATE_SUB_KEY access rights.

winreg.KEY_READ
Combines the STANDARD_RIGHTS_READ, KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS, and KEY_NOTIFY values.

winreg.KEY_EXECUTE
Equivalent to KEY_READ.

winreg.KEY_QUERY_VALUE
Required to query the values of a registry key.

winreg.KEY_SET_VALUE
Required to create, delete, or set a registry value.

winreg.KEY_CREATE_SUB_KEY
Required to create a subkey of a registry key.

winreg.KEY_ENUMERATE_SUB_KEYS
Required to enumerate the subkeys of a registry key.

winreg.KEY_NOTIFY
Required to request change notifications for a registry key or for subkeys of a registry key.

winreg.KEY_CREATE_LINK
Reserved for system use.
 64-bit Specific For more information, see Accessing an Alternate Registry View.
winreg.KEY_WOW64_64KEY
Indicates that an application on 64-bit Windows should operate on the 64-bit registry view.

winreg.KEY_WOW64_32KEY
Indicates that an application on 64-bit Windows should operate on the 32-bit registry view.
 Value Types For more information, see Registry Value Types.
winreg.REG_BINARY
Binary data in any form.

winreg.REG_DWORD
32-bit number.

winreg.REG_DWORD_LITTLE_ENDIAN
A 32-bit number in little-endian format. Equivalent to REG_DWORD.

winreg.REG_DWORD_BIG_ENDIAN
A 32-bit number in big-endian format.

winreg.REG_EXPAND_SZ
Null-terminated string containing references to environment variables (%PATH%).

winreg.REG_LINK
A Unicode symbolic link.

winreg.REG_MULTI_SZ
A sequence of null-terminated strings, terminated by two null characters. (Python handles this termination automatically.)

winreg.REG_NONE
No defined value type.

winreg.REG_QWORD
A 64-bit number.  New in version 3.6.

winreg.REG_QWORD_LITTLE_ENDIAN
A 64-bit number in little-endian format. Equivalent to REG_QWORD.  New in version 3.6.

winreg.REG_RESOURCE_LIST
A device-driver resource list.

winreg.REG_FULL_RESOURCE_DESCRIPTOR
A hardware setting.

winreg.REG_RESOURCE_REQUIREMENTS_LIST
A hardware resource list.

winreg.REG_SZ
A null-terminated string.
 Registry Handle Objects This object wraps a Windows HKEY object, automatically closing it when the object is destroyed. To guarantee cleanup, you can call either the Close() method on the object, or the CloseKey() function. All registry functions in this module return one of these objects. All registry functions in this module which accept a handle object also accept an integer, however, use of the handle object is encouraged. Handle objects provide semantics for __bool__() – thus if handle:
    print("Yes")
 will print Yes if the handle is currently valid (has not been closed or detached). The object also support comparison semantics, so handle objects will compare true if they both reference the same underlying Windows handle value. Handle objects can be converted to an integer (e.g., using the built-in int() function), in which case the underlying Windows handle value is returned. You can also use the Detach() method to return the integer handle, and also disconnect the Windows handle from the handle object.
PyHKEY.Close()
Closes the underlying Windows handle. If the handle is already closed, no error is raised.

PyHKEY.Detach()
Detaches the Windows handle from the handle object. The result is an integer that holds the value of the handle before it is detached. If the handle is already detached or closed, this will return zero. After calling this function, the handle is effectively invalidated, but the handle is not closed. You would call this function when you need the underlying Win32 handle to exist beyond the lifetime of the handle object. Raises an auditing event winreg.PyHKEY.Detach with argument key.

PyHKEY.__enter__()
PyHKEY.__exit__(*exc_info)
The HKEY object implements __enter__() and __exit__() and thus supports the context protocol for the with statement: with OpenKey(HKEY_LOCAL_MACHINE, "foo") as key:
    ...  # work with key
 will automatically close key when control leaves the with block.


winreg.CloseKey(hkey)
Closes a previously opened registry key. The hkey argument specifies a previously opened key.  Note If hkey is not closed using this method (or via hkey.Close()), it is closed when the hkey object is destroyed by Python.


winreg.ConnectRegistry(computer_name, key)
Establishes a connection to a predefined registry handle on another computer, and returns a handle object. computer_name is the name of the remote computer, of the form r"\\computername". If None, the local computer is used. key is the predefined handle to connect to. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.ConnectRegistry with arguments computer_name, key.  Changed in version 3.3: See above.


winreg.CreateKey(key, sub_key)
Creates or opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the key this method opens or creates. If key is one of the predefined keys, sub_key may be None. In that case, the handle returned is the same key handle passed in to the function. If the key already exists, this function opens the existing key. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.CreateKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  Changed in version 3.3: See above.


winreg.CreateKeyEx(key, sub_key, reserved=0, access=KEY_WRITE)
Creates or opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the key this method opens or creates. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_WRITE. See Access Rights for other allowed values. If key is one of the predefined keys, sub_key may be None. In that case, the handle returned is the same key handle passed in to the function. If the key already exists, this function opens the existing key. The return value is the handle of the opened key. If the function fails, an OSError exception is raised. Raises an auditing event winreg.CreateKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  New in version 3.2.   Changed in version 3.3: See above.


winreg.DeleteKey(key, sub_key)
Deletes the specified key. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that must be a subkey of the key identified by the key parameter. This value must not be None, and the key may not have subkeys. This method can not delete keys with subkeys. If the method succeeds, the entire key, including all of its values, is removed. If the method fails, an OSError exception is raised. Raises an auditing event winreg.DeleteKey with arguments key, sub_key, access.  Changed in version 3.3: See above.


winreg.DeleteKeyEx(key, sub_key, access=KEY_WOW64_64KEY, reserved=0)
Deletes the specified key.  Note The DeleteKeyEx() function is implemented with the RegDeleteKeyEx Windows API function, which is specific to 64-bit versions of Windows. See the RegDeleteKeyEx documentation.  key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that must be a subkey of the key identified by the key parameter. This value must not be None, and the key may not have subkeys. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_WOW64_64KEY. See Access Rights for other allowed values. This method can not delete keys with subkeys. If the method succeeds, the entire key, including all of its values, is removed. If the method fails, an OSError exception is raised. On unsupported Windows versions, NotImplementedError is raised. Raises an auditing event winreg.DeleteKey with arguments key, sub_key, access.  New in version 3.2.   Changed in version 3.3: See above.


winreg.DeleteValue(key, value)
Removes a named value from a registry key. key is an already open key, or one of the predefined HKEY_* constants. value is a string that identifies the value to remove. Raises an auditing event winreg.DeleteValue with arguments key, value.


winreg.DisableReflectionKey(key)
Disables registry reflection for 32-bit processes running on a 64-bit operating system. key is an already open key, or one of the predefined HKEY_* constants. Will generally raise NotImplementedError if executed on a 32-bit operating system. If the key is not on the reflection list, the function succeeds but has no effect. Disabling reflection for a key does not affect reflection of any subkeys. Raises an auditing event winreg.DisableReflectionKey with argument key.


winreg.EnableReflectionKey(key)
Restores registry reflection for the specified disabled key. key is an already open key, or one of the predefined HKEY_* constants. Will generally raise NotImplementedError if executed on a 32-bit operating system. Restoring reflection for a key does not affect reflection of any subkeys. Raises an auditing event winreg.EnableReflectionKey with argument key.


winreg.EnumKey(key, index)
Enumerates subkeys of an open registry key, returning a string. key is an already open key, or one of the predefined HKEY_* constants. index is an integer that identifies the index of the key to retrieve. The function retrieves the name of one subkey each time it is called. It is typically called repeatedly until an OSError exception is raised, indicating, no more values are available. Raises an auditing event winreg.EnumKey with arguments key, index.  Changed in version 3.3: See above.


winreg.EnumValue(key, index)
Enumerates values of an open registry key, returning a tuple. key is an already open key, or one of the predefined HKEY_* constants. index is an integer that identifies the index of the value to retrieve. The function retrieves the name of one subkey each time it is called. It is typically called repeatedly, until an OSError exception is raised, indicating no more values. The result is a tuple of 3 items:
Index Meaning
0 A string that identifies the value name
1 An object that holds the value data, and whose type depends on the underlying registry type
2 An integer that identifies the type of the value data (see table in docs for SetValueEx())   Raises an auditing event winreg.EnumValue with arguments key, index.  Changed in version 3.3: See above.


winreg.ExpandEnvironmentStrings(str)
Expands environment variable placeholders %NAME% in strings like REG_EXPAND_SZ: >>> ExpandEnvironmentStrings('%windir%')
'C:\\Windows'
 Raises an auditing event winreg.ExpandEnvironmentStrings with argument str.


winreg.FlushKey(key)
Writes all the attributes of a key to the registry. key is an already open key, or one of the predefined HKEY_* constants. It is not necessary to call FlushKey() to change a key. Registry changes are flushed to disk by the registry using its lazy flusher. Registry changes are also flushed to disk at system shutdown. Unlike CloseKey(), the FlushKey() method returns only when all the data has been written to the registry. An application should only call FlushKey() if it requires absolute certainty that registry changes are on disk.  Note If you don’t know whether a FlushKey() call is required, it probably isn’t.


winreg.HKEY_CLASSES_ROOT
Registry entries subordinate to this key define types (or classes) of documents and the properties associated with those types. Shell and COM applications use the information stored under this key.


winreg.HKEY_CURRENT_CONFIG
Contains information about the current hardware profile of the local computer system.


winreg.HKEY_CURRENT_USER
Registry entries subordinate to this key define the preferences of the current user. These preferences include the settings of environment variables, data about program groups, colors, printers, network connections, and application preferences.


winreg.HKEY_DYN_DATA
This key is not used in versions of Windows after 98.


winreg.HKEY_LOCAL_MACHINE
Registry entries subordinate to this key define the physical state of the computer, including data about the bus type, system memory, and installed hardware and software.


winreg.HKEY_PERFORMANCE_DATA
Registry entries subordinate to this key allow you to access performance data. The data is not actually stored in the registry; the registry functions cause the system to collect the data from its source.


winreg.HKEY_USERS
Registry entries subordinate to this key define the default user configuration for new users on the local computer and the user configuration for the current user.


winreg.KEY_ALL_ACCESS
Combines the STANDARD_RIGHTS_REQUIRED, KEY_QUERY_VALUE, KEY_SET_VALUE, KEY_CREATE_SUB_KEY, KEY_ENUMERATE_SUB_KEYS, KEY_NOTIFY, and KEY_CREATE_LINK access rights.


winreg.KEY_CREATE_LINK
Reserved for system use.


winreg.KEY_CREATE_SUB_KEY
Required to create a subkey of a registry key.


winreg.KEY_ENUMERATE_SUB_KEYS
Required to enumerate the subkeys of a registry key.


winreg.KEY_EXECUTE
Equivalent to KEY_READ.


winreg.KEY_NOTIFY
Required to request change notifications for a registry key or for subkeys of a registry key.


winreg.KEY_QUERY_VALUE
Required to query the values of a registry key.


winreg.KEY_READ
Combines the STANDARD_RIGHTS_READ, KEY_QUERY_VALUE, KEY_ENUMERATE_SUB_KEYS, and KEY_NOTIFY values.


winreg.KEY_SET_VALUE
Required to create, delete, or set a registry value.


winreg.KEY_WOW64_32KEY
Indicates that an application on 64-bit Windows should operate on the 32-bit registry view.


winreg.KEY_WOW64_64KEY
Indicates that an application on 64-bit Windows should operate on the 64-bit registry view.


winreg.KEY_WRITE
Combines the STANDARD_RIGHTS_WRITE, KEY_SET_VALUE, and KEY_CREATE_SUB_KEY access rights.


winreg.LoadKey(key, sub_key, file_name)
Creates a subkey under the specified key and stores registration information from a specified file into that subkey. key is a handle returned by ConnectRegistry() or one of the constants HKEY_USERS or HKEY_LOCAL_MACHINE. sub_key is a string that identifies the subkey to load. file_name is the name of the file to load registry data from. This file must have been created with the SaveKey() function. Under the file allocation table (FAT) file system, the filename may not have an extension. A call to LoadKey() fails if the calling process does not have the SE_RESTORE_PRIVILEGE privilege. Note that privileges are different from permissions – see the RegLoadKey documentation for more details. If key is a handle returned by ConnectRegistry(), then the path specified in file_name is relative to the remote computer. Raises an auditing event winreg.LoadKey with arguments key, sub_key, file_name.


winreg.OpenKey(key, sub_key, reserved=0, access=KEY_READ)
winreg.OpenKeyEx(key, sub_key, reserved=0, access=KEY_READ)
Opens the specified key, returning a handle object. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that identifies the sub_key to open. reserved is a reserved integer, and must be zero. The default is zero. access is an integer that specifies an access mask that describes the desired security access for the key. Default is KEY_READ. See Access Rights for other allowed values. The result is a new handle to the specified key. If the function fails, OSError is raised. Raises an auditing event winreg.OpenKey with arguments key, sub_key, access. Raises an auditing event winreg.OpenKey/result with argument key.  Changed in version 3.2: Allow the use of named arguments.   Changed in version 3.3: See above.


PyHKEY.Close()
Closes the underlying Windows handle. If the handle is already closed, no error is raised.


PyHKEY.Detach()
Detaches the Windows handle from the handle object. The result is an integer that holds the value of the handle before it is detached. If the handle is already detached or closed, this will return zero. After calling this function, the handle is effectively invalidated, but the handle is not closed. You would call this function when you need the underlying Win32 handle to exist beyond the lifetime of the handle object. Raises an auditing event winreg.PyHKEY.Detach with argument key.


PyHKEY.__enter__()
PyHKEY.__exit__(*exc_info)
The HKEY object implements __enter__() and __exit__() and thus supports the context protocol for the with statement: with OpenKey(HKEY_LOCAL_MACHINE, "foo") as key:
    ...  # work with key
 will automatically close key when control leaves the with block.


winreg.QueryInfoKey(key)
Returns information about a key, as a tuple. key is an already open key, or one of the predefined HKEY_* constants. The result is a tuple of 3 items:
Index Meaning
0 An integer giving the number of sub keys this key has.
1 An integer giving the number of values this key has.
2 An integer giving when the key was last modified (if available) as 100’s of nanoseconds since Jan 1, 1601.   Raises an auditing event winreg.QueryInfoKey with argument key.


winreg.QueryReflectionKey(key)
Determines the reflection state for the specified key. key is an already open key, or one of the predefined HKEY_* constants. Returns True if reflection is disabled. Will generally raise NotImplementedError if executed on a 32-bit operating system. Raises an auditing event winreg.QueryReflectionKey with argument key.


winreg.QueryValue(key, sub_key)
Retrieves the unnamed value for a key, as a string. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that holds the name of the subkey with which the value is associated. If this parameter is None or empty, the function retrieves the value set by the SetValue() method for the key identified by key. Values in the registry have name, type, and data components. This method retrieves the data for a key’s first value that has a NULL name. But the underlying API call doesn’t return the type, so always use QueryValueEx() if possible. Raises an auditing event winreg.QueryValue with arguments key, sub_key, value_name.


winreg.QueryValueEx(key, value_name)
Retrieves the type and data for a specified value name associated with an open registry key. key is an already open key, or one of the predefined HKEY_* constants. value_name is a string indicating the value to query. The result is a tuple of 2 items:
Index Meaning
0 The value of the registry item.
1 An integer giving the registry type for this value (see table in docs for SetValueEx())   Raises an auditing event winreg.QueryValue with arguments key, sub_key, value_name.


winreg.REG_BINARY
Binary data in any form.


winreg.REG_DWORD_BIG_ENDIAN
A 32-bit number in big-endian format.


winreg.REG_DWORD_LITTLE_ENDIAN
A 32-bit number in little-endian format. Equivalent to REG_DWORD.


winreg.REG_EXPAND_SZ
Null-terminated string containing references to environment variables (%PATH%).


winreg.REG_FULL_RESOURCE_DESCRIPTOR
A hardware setting.


winreg.REG_LINK
A Unicode symbolic link.


winreg.REG_MULTI_SZ
A sequence of null-terminated strings, terminated by two null characters. (Python handles this termination automatically.)


winreg.REG_QWORD
A 64-bit number.  New in version 3.6.


winreg.REG_QWORD_LITTLE_ENDIAN
A 64-bit number in little-endian format. Equivalent to REG_QWORD.  New in version 3.6.


winreg.REG_RESOURCE_LIST
A device-driver resource list.


winreg.REG_RESOURCE_REQUIREMENTS_LIST
A hardware resource list.


winreg.SaveKey(key, file_name)
Saves the specified key, and all its subkeys to the specified file. key is an already open key, or one of the predefined HKEY_* constants. file_name is the name of the file to save registry data to. This file cannot already exist. If this filename includes an extension, it cannot be used on file allocation table (FAT) file systems by the LoadKey() method. If key represents a key on a remote computer, the path described by file_name is relative to the remote computer. The caller of this method must possess the SeBackupPrivilege security privilege. Note that privileges are different than permissions – see the Conflicts Between User Rights and Permissions documentation for more details. This function passes NULL for security_attributes to the API. Raises an auditing event winreg.SaveKey with arguments key, file_name.


winreg.SetValue(key, sub_key, type, value)
Associates a value with a specified key. key is an already open key, or one of the predefined HKEY_* constants. sub_key is a string that names the subkey with which the value is associated. type is an integer that specifies the type of the data. Currently this must be REG_SZ, meaning only strings are supported. Use the SetValueEx() function for support for other data types. value is a string that specifies the new value. If the key specified by the sub_key parameter does not exist, the SetValue function creates it. Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the filenames stored in the configuration registry. This helps the registry perform efficiently. The key identified by the key parameter must have been opened with KEY_SET_VALUE access. Raises an auditing event winreg.SetValue with arguments key, sub_key, type, value.


winreg.SetValueEx(key, value_name, reserved, type, value)
Stores data in the value field of an open registry key. key is an already open key, or one of the predefined HKEY_* constants. value_name is a string that names the subkey with which the value is associated. reserved can be anything – zero is always passed to the API. type is an integer that specifies the type of the data. See Value Types for the available types. value is a string that specifies the new value. This method can also set additional value and type information for the specified key. The key identified by the key parameter must have been opened with KEY_SET_VALUE access. To open the key, use the CreateKey() or OpenKey() methods. Value lengths are limited by available memory. Long values (more than 2048 bytes) should be stored as files with the filenames stored in the configuration registry. This helps the registry perform efficiently. Raises an auditing event winreg.SetValue with arguments key, sub_key, type, value.


winsound — Sound-playing interface for Windows The winsound module provides access to the basic sound-playing machinery provided by Windows platforms. It includes functions and several constants.
winsound.Beep(frequency, duration)
Beep the PC’s speaker. The frequency parameter specifies frequency, in hertz, of the sound, and must be in the range 37 through 32,767. The duration parameter specifies the number of milliseconds the sound should last. If the system is not able to beep the speaker, RuntimeError is raised.

winsound.PlaySound(sound, flags)
Call the underlying PlaySound() function from the Platform API. The sound parameter may be a filename, a system sound alias, audio data as a bytes-like object, or None. Its interpretation depends on the value of flags, which can be a bitwise ORed combination of the constants described below. If the sound parameter is None, any currently playing waveform sound is stopped. If the system indicates an error, RuntimeError is raised.

winsound.MessageBeep(type=MB_OK)
Call the underlying MessageBeep() function from the Platform API. This plays a sound as specified in the registry. The type argument specifies which sound to play; possible values are -1, MB_ICONASTERISK, MB_ICONEXCLAMATION, MB_ICONHAND, MB_ICONQUESTION, and MB_OK, all described below. The value -1 produces a “simple beep”; this is the final fallback if a sound cannot be played otherwise. If the system indicates an error, RuntimeError is raised.

winsound.SND_FILENAME
The sound parameter is the name of a WAV file. Do not use with SND_ALIAS.

winsound.SND_ALIAS
The sound parameter is a sound association name from the registry. If the registry contains no such name, play the system default sound unless SND_NODEFAULT is also specified. If no default sound is registered, raise RuntimeError. Do not use with SND_FILENAME. All Win32 systems support at least the following; most systems support many more:
PlaySound() name Corresponding Control Panel Sound name
'SystemAsterisk' Asterisk
'SystemExclamation' Exclamation
'SystemExit' Exit Windows
'SystemHand' Critical Stop
'SystemQuestion' Question   For example: import winsound
# Play Windows exit sound.
winsound.PlaySound("SystemExit", winsound.SND_ALIAS)

# Probably play Windows default sound, if any is registered (because
# "*" probably isn't the registered name of any sound).
winsound.PlaySound("*", winsound.SND_ALIAS)

winsound.SND_LOOP
Play the sound repeatedly. The SND_ASYNC flag must also be used to avoid blocking. Cannot be used with SND_MEMORY.

winsound.SND_MEMORY
The sound parameter to PlaySound() is a memory image of a WAV file, as a bytes-like object.  Note This module does not support playing from a memory image asynchronously, so a combination of this flag and SND_ASYNC will raise RuntimeError.

winsound.SND_PURGE
Stop playing all instances of the specified sound.  Note This flag is not supported on modern Windows platforms.

winsound.SND_ASYNC
Return immediately, allowing sounds to play asynchronously.

winsound.SND_NODEFAULT
If the specified sound cannot be found, do not play the system default sound.

winsound.SND_NOSTOP
Do not interrupt sounds currently playing.

winsound.SND_NOWAIT
Return immediately if the sound driver is busy.  Note This flag is not supported on modern Windows platforms.

winsound.MB_ICONASTERISK
Play the SystemDefault sound.

winsound.MB_ICONEXCLAMATION
Play the SystemExclamation sound.

winsound.MB_ICONHAND
Play the SystemHand sound.

winsound.MB_ICONQUESTION
Play the SystemQuestion sound.

winsound.MB_OK
Play the SystemDefault sound.


winsound.Beep(frequency, duration)
Beep the PC’s speaker. The frequency parameter specifies frequency, in hertz, of the sound, and must be in the range 37 through 32,767. The duration parameter specifies the number of milliseconds the sound should last. If the system is not able to beep the speaker, RuntimeError is raised.


winsound.MB_ICONASTERISK
Play the SystemDefault sound.


winsound.MB_ICONEXCLAMATION
Play the SystemExclamation sound.


winsound.MB_ICONHAND
Play the SystemHand sound.


winsound.MB_ICONQUESTION
Play the SystemQuestion sound.


winsound.MB_OK
Play the SystemDefault sound.


winsound.MessageBeep(type=MB_OK)
Call the underlying MessageBeep() function from the Platform API. This plays a sound as specified in the registry. The type argument specifies which sound to play; possible values are -1, MB_ICONASTERISK, MB_ICONEXCLAMATION, MB_ICONHAND, MB_ICONQUESTION, and MB_OK, all described below. The value -1 produces a “simple beep”; this is the final fallback if a sound cannot be played otherwise. If the system indicates an error, RuntimeError is raised.


winsound.PlaySound(sound, flags)
Call the underlying PlaySound() function from the Platform API. The sound parameter may be a filename, a system sound alias, audio data as a bytes-like object, or None. Its interpretation depends on the value of flags, which can be a bitwise ORed combination of the constants described below. If the sound parameter is None, any currently playing waveform sound is stopped. If the system indicates an error, RuntimeError is raised.


winsound.SND_ALIAS
The sound parameter is a sound association name from the registry. If the registry contains no such name, play the system default sound unless SND_NODEFAULT is also specified. If no default sound is registered, raise RuntimeError. Do not use with SND_FILENAME. All Win32 systems support at least the following; most systems support many more:
PlaySound() name Corresponding Control Panel Sound name
'SystemAsterisk' Asterisk
'SystemExclamation' Exclamation
'SystemExit' Exit Windows
'SystemHand' Critical Stop
'SystemQuestion' Question   For example: import winsound
# Play Windows exit sound.
winsound.PlaySound("SystemExit", winsound.SND_ALIAS)

# Probably play Windows default sound, if any is registered (because
# "*" probably isn't the registered name of any sound).
winsound.PlaySound("*", winsound.SND_ALIAS)


winsound.SND_ASYNC
Return immediately, allowing sounds to play asynchronously.


winsound.SND_FILENAME
The sound parameter is the name of a WAV file. Do not use with SND_ALIAS.


winsound.SND_LOOP
Play the sound repeatedly. The SND_ASYNC flag must also be used to avoid blocking. Cannot be used with SND_MEMORY.


winsound.SND_MEMORY
The sound parameter to PlaySound() is a memory image of a WAV file, as a bytes-like object.  Note This module does not support playing from a memory image asynchronously, so a combination of this flag and SND_ASYNC will raise RuntimeError.


winsound.SND_NODEFAULT
If the specified sound cannot be found, do not play the system default sound.


winsound.SND_NOSTOP
Do not interrupt sounds currently playing.


winsound.SND_NOWAIT
Return immediately if the sound driver is busy.  Note This flag is not supported on modern Windows platforms.


winsound.SND_PURGE
Stop playing all instances of the specified sound.  Note This flag is not supported on modern Windows platforms.


wsgiref — WSGI Utilities and Reference Implementation The Web Server Gateway Interface (WSGI) is a standard interface between web server software and web applications written in Python. Having a standard interface makes it easy to use an application that supports WSGI with a number of different web servers. Only authors of web servers and programming frameworks need to know every detail and corner case of the WSGI design. You don’t need to understand every detail of WSGI just to install a WSGI application or to write a web application using an existing framework. wsgiref is a reference implementation of the WSGI specification that can be used to add WSGI support to a web server or framework. It provides utilities for manipulating WSGI environment variables and response headers, base classes for implementing WSGI servers, a demo HTTP server that serves WSGI applications, and a validation tool that checks WSGI servers and applications for conformance to the WSGI specification (PEP 3333). See wsgi.readthedocs.io for more information about WSGI, and links to tutorials and other resources. wsgiref.util – WSGI environment utilities This module provides a variety of utility functions for working with WSGI environments. A WSGI environment is a dictionary containing HTTP request variables as described in PEP 3333. All of the functions taking an environ parameter expect a WSGI-compliant dictionary to be supplied; please see PEP 3333 for a detailed specification.
wsgiref.util.guess_scheme(environ)
Return a guess for whether wsgi.url_scheme should be “http” or “https”, by checking for a HTTPS environment variable in the environ dictionary. The return value is a string. This function is useful when creating a gateway that wraps CGI or a CGI-like protocol such as FastCGI. Typically, servers providing such protocols will include a HTTPS variable with a value of “1”, “yes”, or “on” when a request is received via SSL. So, this function returns “https” if such a value is found, and “http” otherwise.

wsgiref.util.request_uri(environ, include_query=True)
Return the full request URI, optionally including the query string, using the algorithm found in the “URL Reconstruction” section of PEP 3333. If include_query is false, the query string is not included in the resulting URI.

wsgiref.util.application_uri(environ)
Similar to request_uri(), except that the PATH_INFO and QUERY_STRING variables are ignored. The result is the base URI of the application object addressed by the request.

wsgiref.util.shift_path_info(environ)
Shift a single name from PATH_INFO to SCRIPT_NAME and return the name. The environ dictionary is modified in-place; use a copy if you need to keep the original PATH_INFO or SCRIPT_NAME intact. If there are no remaining path segments in PATH_INFO, None is returned. Typically, this routine is used to process each portion of a request URI path, for example to treat the path as a series of dictionary keys. This routine modifies the passed-in environment to make it suitable for invoking another WSGI application that is located at the target URI. For example, if there is a WSGI application at /foo, and the request URI path is /foo/bar/baz, and the WSGI application at /foo calls shift_path_info(), it will receive the string “bar”, and the environment will be updated to be suitable for passing to a WSGI application at /foo/bar. That is, SCRIPT_NAME will change from /foo to /foo/bar, and PATH_INFO will change from /bar/baz to /baz. When PATH_INFO is just a “/”, this routine returns an empty string and appends a trailing slash to SCRIPT_NAME, even though empty path segments are normally ignored, and SCRIPT_NAME doesn’t normally end in a slash. This is intentional behavior, to ensure that an application can tell the difference between URIs ending in /x from ones ending in /x/ when using this routine to do object traversal.

wsgiref.util.setup_testing_defaults(environ)
Update environ with trivial defaults for testing purposes. This routine adds various parameters required for WSGI, including HTTP_HOST, SERVER_NAME, SERVER_PORT, REQUEST_METHOD, SCRIPT_NAME, PATH_INFO, and all of the PEP 3333-defined wsgi.* variables. It only supplies default values, and does not replace any existing settings for these variables. This routine is intended to make it easier for unit tests of WSGI servers and applications to set up dummy environments. It should NOT be used by actual WSGI servers or applications, since the data is fake! Example usage: from wsgiref.util import setup_testing_defaults
from wsgiref.simple_server import make_server

# A relatively simple WSGI application. It's going to print out the
# environment dictionary after being updated by setup_testing_defaults
def simple_app(environ, start_response):
    setup_testing_defaults(environ)

    status = '200 OK'
    headers = [('Content-type', 'text/plain; charset=utf-8')]

    start_response(status, headers)

    ret = [("%s: %s\n" % (key, value)).encode("utf-8")
           for key, value in environ.items()]
    return ret

with make_server('', 8000, simple_app) as httpd:
    print("Serving on port 8000...")
    httpd.serve_forever()

 In addition to the environment functions above, the wsgiref.util module also provides these miscellaneous utilities:
wsgiref.util.is_hop_by_hop(header_name)
Return True if ‘header_name’ is an HTTP/1.1 “Hop-by-Hop” header, as defined by RFC 2616.

class wsgiref.util.FileWrapper(filelike, blksize=8192)
A wrapper to convert a file-like object to an iterator. The resulting objects support both __getitem__() and __iter__() iteration styles, for compatibility with Python 2.1 and Jython. As the object is iterated over, the optional blksize parameter will be repeatedly passed to the filelike object’s read() method to obtain bytestrings to yield. When read() returns an empty bytestring, iteration is ended and is not resumable. If filelike has a close() method, the returned object will also have a close() method, and it will invoke the filelike object’s close() method when called. Example usage: from io import StringIO
from wsgiref.util import FileWrapper

# We're using a StringIO-buffer for as the file-like object
filelike = StringIO("This is an example file-like object"*10)
wrapper = FileWrapper(filelike, blksize=5)

for chunk in wrapper:
    print(chunk)
  Deprecated since version 3.8: Support for sequence protocol is deprecated.
 wsgiref.headers – WSGI response header tools This module provides a single class, Headers, for convenient manipulation of WSGI response headers using a mapping-like interface.
class wsgiref.headers.Headers([headers])
Create a mapping-like object wrapping headers, which must be a list of header name/value tuples as described in PEP 3333. The default value of headers is an empty list. Headers objects support typical mapping operations including __getitem__(), get(), __setitem__(), setdefault(), __delitem__() and __contains__(). For each of these methods, the key is the header name (treated case-insensitively), and the value is the first value associated with that header name. Setting a header deletes any existing values for that header, then adds a new value at the end of the wrapped header list. Headers’ existing order is generally maintained, with new headers added to the end of the wrapped list. Unlike a dictionary, Headers objects do not raise an error when you try to get or delete a key that isn’t in the wrapped header list. Getting a nonexistent header just returns None, and deleting a nonexistent header does nothing. Headers objects also support keys(), values(), and items() methods. The lists returned by keys() and items() can include the same key more than once if there is a multi-valued header. The len() of a Headers object is the same as the length of its items(), which is the same as the length of the wrapped header list. In fact, the items() method just returns a copy of the wrapped header list. Calling bytes() on a Headers object returns a formatted bytestring suitable for transmission as HTTP response headers. Each header is placed on a line with its value, separated by a colon and a space. Each line is terminated by a carriage return and line feed, and the bytestring is terminated with a blank line. In addition to their mapping interface and formatting features, Headers objects also have the following methods for querying and adding multi-valued headers, and for adding headers with MIME parameters:
get_all(name)
Return a list of all the values for the named header. The returned list will be sorted in the order they appeared in the original header list or were added to this instance, and may contain duplicates. Any fields deleted and re-inserted are always appended to the header list. If no fields exist with the given name, returns an empty list.

add_header(name, value, **_params)
Add a (possibly multi-valued) header, with optional MIME parameters specified via keyword arguments. name is the header field to add. Keyword arguments can be used to set MIME parameters for the header field. Each parameter must be a string or None. Underscores in parameter names are converted to dashes, since dashes are illegal in Python identifiers, but many MIME parameter names include dashes. If the parameter value is a string, it is added to the header value parameters in the form name="value". If it is None, only the parameter name is added. (This is used for MIME parameters without a value.) Example usage: h.add_header('content-disposition', 'attachment', filename='bud.gif')
 The above will add a header that looks like this: Content-Disposition: attachment; filename="bud.gif"

  Changed in version 3.5: headers parameter is optional.
 wsgiref.simple_server – a simple WSGI HTTP server This module implements a simple HTTP server (based on http.server) that serves WSGI applications. Each server instance serves a single WSGI application on a given host and port. If you want to serve multiple applications on a single host and port, you should create a WSGI application that parses PATH_INFO to select which application to invoke for each request. (E.g., using the shift_path_info() function from wsgiref.util.)
wsgiref.simple_server.make_server(host, port, app, server_class=WSGIServer, handler_class=WSGIRequestHandler)
Create a new WSGI server listening on host and port, accepting connections for app. The return value is an instance of the supplied server_class, and will process requests using the specified handler_class. app must be a WSGI application object, as defined by PEP 3333. Example usage: from wsgiref.simple_server import make_server, demo_app

with make_server('', 8000, demo_app) as httpd:
    print("Serving HTTP on port 8000...")

    # Respond to requests until process is killed
    httpd.serve_forever()

    # Alternative: serve one request, then exit
    httpd.handle_request()

wsgiref.simple_server.demo_app(environ, start_response)
This function is a small but complete WSGI application that returns a text page containing the message “Hello world!” and a list of the key/value pairs provided in the environ parameter. It’s useful for verifying that a WSGI server (such as wsgiref.simple_server) is able to run a simple WSGI application correctly.

class wsgiref.simple_server.WSGIServer(server_address, RequestHandlerClass)
Create a WSGIServer instance. server_address should be a (host,port) tuple, and RequestHandlerClass should be the subclass of http.server.BaseHTTPRequestHandler that will be used to process requests. You do not normally need to call this constructor, as the make_server() function can handle all the details for you. WSGIServer is a subclass of http.server.HTTPServer, so all of its methods (such as serve_forever() and handle_request()) are available. WSGIServer also provides these WSGI-specific methods:
set_app(application)
Sets the callable application as the WSGI application that will receive requests.

get_app()
Returns the currently-set application callable.
 Normally, however, you do not need to use these additional methods, as set_app() is normally called by make_server(), and the get_app() exists mainly for the benefit of request handler instances.

class wsgiref.simple_server.WSGIRequestHandler(request, client_address, server)
Create an HTTP handler for the given request (i.e. a socket), client_address (a (host,port) tuple), and server (WSGIServer instance). You do not need to create instances of this class directly; they are automatically created as needed by WSGIServer objects. You can, however, subclass this class and supply it as a handler_class to the make_server() function. Some possibly relevant methods for overriding in subclasses:
get_environ()
Returns a dictionary containing the WSGI environment for a request. The default implementation copies the contents of the WSGIServer object’s base_environ dictionary attribute and then adds various headers derived from the HTTP request. Each call to this method should return a new dictionary containing all of the relevant CGI environment variables as specified in PEP 3333.

get_stderr()
Return the object that should be used as the wsgi.errors stream. The default implementation just returns sys.stderr.

handle()
Process the HTTP request. The default implementation creates a handler instance using a wsgiref.handlers class to implement the actual WSGI application interface.

 wsgiref.validate — WSGI conformance checker When creating new WSGI application objects, frameworks, servers, or middleware, it can be useful to validate the new code’s conformance using wsgiref.validate. This module provides a function that creates WSGI application objects that validate communications between a WSGI server or gateway and a WSGI application object, to check both sides for protocol conformance. Note that this utility does not guarantee complete PEP 3333 compliance; an absence of errors from this module does not necessarily mean that errors do not exist. However, if this module does produce an error, then it is virtually certain that either the server or application is not 100% compliant. This module is based on the paste.lint module from Ian Bicking’s “Python Paste” library.
wsgiref.validate.validator(application)
Wrap application and return a new WSGI application object. The returned application will forward all requests to the original application, and will check that both the application and the server invoking it are conforming to the WSGI specification and to RFC 2616. Any detected nonconformance results in an AssertionError being raised; note, however, that how these errors are handled is server-dependent. For example, wsgiref.simple_server and other servers based on wsgiref.handlers (that don’t override the error handling methods to do something else) will simply output a message that an error has occurred, and dump the traceback to sys.stderr or some other error stream. This wrapper may also generate output using the warnings module to indicate behaviors that are questionable but which may not actually be prohibited by PEP 3333. Unless they are suppressed using Python command-line options or the warnings API, any such warnings will be written to sys.stderr (not wsgi.errors, unless they happen to be the same object). Example usage: from wsgiref.validate import validator
from wsgiref.simple_server import make_server

# Our callable object which is intentionally not compliant to the
# standard, so the validator is going to break
def simple_app(environ, start_response):
    status = '200 OK'  # HTTP Status
    headers = [('Content-type', 'text/plain')]  # HTTP Headers
    start_response(status, headers)

    # This is going to break because we need to return a list, and
    # the validator is going to inform us
    return b"Hello World"

# This is the application wrapped in a validator
validator_app = validator(simple_app)

with make_server('', 8000, validator_app) as httpd:
    print("Listening on port 8000....")
    httpd.serve_forever()

 wsgiref.handlers – server/gateway base classes This module provides base handler classes for implementing WSGI servers and gateways. These base classes handle most of the work of communicating with a WSGI application, as long as they are given a CGI-like environment, along with input, output, and error streams.
class wsgiref.handlers.CGIHandler
CGI-based invocation via sys.stdin, sys.stdout, sys.stderr and os.environ. This is useful when you have a WSGI application and want to run it as a CGI script. Simply invoke CGIHandler().run(app), where app is the WSGI application object you wish to invoke. This class is a subclass of BaseCGIHandler that sets wsgi.run_once to true, wsgi.multithread to false, and wsgi.multiprocess to true, and always uses sys and os to obtain the necessary CGI streams and environment.

class wsgiref.handlers.IISCGIHandler
A specialized alternative to CGIHandler, for use when deploying on Microsoft’s IIS web server, without having set the config allowPathInfo option (IIS>=7) or metabase allowPathInfoForScriptMappings (IIS<7). By default, IIS gives a PATH_INFO that duplicates the SCRIPT_NAME at the front, causing problems for WSGI applications that wish to implement routing. This handler strips any such duplicated path. IIS can be configured to pass the correct PATH_INFO, but this causes another bug where PATH_TRANSLATED is wrong. Luckily this variable is rarely used and is not guaranteed by WSGI. On IIS<7, though, the setting can only be made on a vhost level, affecting all other script mappings, many of which break when exposed to the PATH_TRANSLATED bug. For this reason IIS<7 is almost never deployed with the fix (Even IIS7 rarely uses it because there is still no UI for it.). There is no way for CGI code to tell whether the option was set, so a separate handler class is provided. It is used in the same way as CGIHandler, i.e., by calling IISCGIHandler().run(app), where app is the WSGI application object you wish to invoke.  New in version 3.2.

class wsgiref.handlers.BaseCGIHandler(stdin, stdout, stderr, environ, multithread=True, multiprocess=False)
Similar to CGIHandler, but instead of using the sys and os modules, the CGI environment and I/O streams are specified explicitly. The multithread and multiprocess values are used to set the wsgi.multithread and wsgi.multiprocess flags for any applications run by the handler instance. This class is a subclass of SimpleHandler intended for use with software other than HTTP “origin servers”. If you are writing a gateway protocol implementation (such as CGI, FastCGI, SCGI, etc.) that uses a Status: header to send an HTTP status, you probably want to subclass this instead of SimpleHandler.

class wsgiref.handlers.SimpleHandler(stdin, stdout, stderr, environ, multithread=True, multiprocess=False)
Similar to BaseCGIHandler, but designed for use with HTTP origin servers. If you are writing an HTTP server implementation, you will probably want to subclass this instead of BaseCGIHandler. This class is a subclass of BaseHandler. It overrides the __init__(), get_stdin(), get_stderr(), add_cgi_vars(), _write(), and _flush() methods to support explicitly setting the environment and streams via the constructor. The supplied environment and streams are stored in the stdin, stdout, stderr, and environ attributes. The write() method of stdout should write each chunk in full, like io.BufferedIOBase.

class wsgiref.handlers.BaseHandler
This is an abstract base class for running WSGI applications. Each instance will handle a single HTTP request, although in principle you could create a subclass that was reusable for multiple requests. BaseHandler instances have only one method intended for external use:
run(app)
Run the specified WSGI application, app.
 All of the other BaseHandler methods are invoked by this method in the process of running the application, and thus exist primarily to allow customizing the process. The following methods MUST be overridden in a subclass:
_write(data)
Buffer the bytes data for transmission to the client. It’s okay if this method actually transmits the data; BaseHandler just separates write and flush operations for greater efficiency when the underlying system actually has such a distinction.

_flush()
Force buffered data to be transmitted to the client. It’s okay if this method is a no-op (i.e., if _write() actually sends the data).

get_stdin()
Return an input stream object suitable for use as the wsgi.input of the request currently being processed.

get_stderr()
Return an output stream object suitable for use as the wsgi.errors of the request currently being processed.

add_cgi_vars()
Insert CGI variables for the current request into the environ attribute.
 Here are some other methods and attributes you may wish to override. This list is only a summary, however, and does not include every method that can be overridden. You should consult the docstrings and source code for additional information before attempting to create a customized BaseHandler subclass. Attributes and methods for customizing the WSGI environment:
wsgi_multithread
The value to be used for the wsgi.multithread environment variable. It defaults to true in BaseHandler, but may have a different default (or be set by the constructor) in the other subclasses.

wsgi_multiprocess
The value to be used for the wsgi.multiprocess environment variable. It defaults to true in BaseHandler, but may have a different default (or be set by the constructor) in the other subclasses.

wsgi_run_once
The value to be used for the wsgi.run_once environment variable. It defaults to false in BaseHandler, but CGIHandler sets it to true by default.

os_environ
The default environment variables to be included in every request’s WSGI environment. By default, this is a copy of os.environ at the time that wsgiref.handlers was imported, but subclasses can either create their own at the class or instance level. Note that the dictionary should be considered read-only, since the default value is shared between multiple classes and instances.

server_software
If the origin_server attribute is set, this attribute’s value is used to set the default SERVER_SOFTWARE WSGI environment variable, and also to set a default Server: header in HTTP responses. It is ignored for handlers (such as BaseCGIHandler and CGIHandler) that are not HTTP origin servers.  Changed in version 3.3: The term “Python” is replaced with implementation specific term like “CPython”, “Jython” etc.

get_scheme()
Return the URL scheme being used for the current request. The default implementation uses the guess_scheme() function from wsgiref.util to guess whether the scheme should be “http” or “https”, based on the current request’s environ variables.

setup_environ()
Set the environ attribute to a fully-populated WSGI environment. The default implementation uses all of the above methods and attributes, plus the get_stdin(), get_stderr(), and add_cgi_vars() methods and the wsgi_file_wrapper attribute. It also inserts a SERVER_SOFTWARE key if not present, as long as the origin_server attribute is a true value and the server_software attribute is set.
 Methods and attributes for customizing exception handling:
log_exception(exc_info)
Log the exc_info tuple in the server log. exc_info is a (type, value,
traceback) tuple. The default implementation simply writes the traceback to the request’s wsgi.errors stream and flushes it. Subclasses can override this method to change the format or retarget the output, mail the traceback to an administrator, or whatever other action may be deemed suitable.

traceback_limit
The maximum number of frames to include in tracebacks output by the default log_exception() method. If None, all frames are included.

error_output(environ, start_response)
This method is a WSGI application to generate an error page for the user. It is only invoked if an error occurs before headers are sent to the client. This method can access the current error information using sys.exc_info(), and should pass that information to start_response when calling it (as described in the “Error Handling” section of PEP 3333). The default implementation just uses the error_status, error_headers, and error_body attributes to generate an output page. Subclasses can override this to produce more dynamic error output. Note, however, that it’s not recommended from a security perspective to spit out diagnostics to any old user; ideally, you should have to do something special to enable diagnostic output, which is why the default implementation doesn’t include any.

error_status
The HTTP status used for error responses. This should be a status string as defined in PEP 3333; it defaults to a 500 code and message.

error_headers
The HTTP headers used for error responses. This should be a list of WSGI response headers ((name, value) tuples), as described in PEP 3333. The default list just sets the content type to text/plain.

error_body
The error response body. This should be an HTTP response body bytestring. It defaults to the plain text, “A server error occurred. Please contact the administrator.”
 Methods and attributes for PEP 3333’s “Optional Platform-Specific File Handling” feature:
wsgi_file_wrapper
A wsgi.file_wrapper factory, or None. The default value of this attribute is the wsgiref.util.FileWrapper class.

sendfile()
Override to implement platform-specific file transmission. This method is called only if the application’s return value is an instance of the class specified by the wsgi_file_wrapper attribute. It should return a true value if it was able to successfully transmit the file, so that the default transmission code will not be executed. The default implementation of this method just returns a false value.
 Miscellaneous methods and attributes:
origin_server
This attribute should be set to a true value if the handler’s _write() and _flush() are being used to communicate directly to the client, rather than via a CGI-like gateway protocol that wants the HTTP status in a special Status: header. This attribute’s default value is true in BaseHandler, but false in BaseCGIHandler and CGIHandler.

http_version
If origin_server is true, this string attribute is used to set the HTTP version of the response set to the client. It defaults to "1.0".

wsgiref.handlers.read_environ()
Transcode CGI variables from os.environ to PEP 3333 “bytes in unicode” strings, returning a new dictionary. This function is used by CGIHandler and IISCGIHandler in place of directly using os.environ, which is not necessarily WSGI-compliant on all platforms and web servers using Python 3 – specifically, ones where the OS’s actual environment is Unicode (i.e. Windows), or ones where the environment is bytes, but the system encoding used by Python to decode it is anything other than ISO-8859-1 (e.g. Unix systems using UTF-8). If you are implementing a CGI-based handler of your own, you probably want to use this routine instead of just copying values out of os.environ directly.  New in version 3.2.
 Examples This is a working “Hello World” WSGI application: from wsgiref.simple_server import make_server

# Every WSGI application must have an application object - a callable
# object that accepts two arguments. For that purpose, we're going to
# use a function (note that you're not limited to a function, you can
# use a class for example). The first argument passed to the function
# is a dictionary containing CGI-style environment variables and the
# second variable is the callable object.
def hello_world_app(environ, start_response):
    status = '200 OK'  # HTTP Status
    headers = [('Content-type', 'text/plain; charset=utf-8')]  # HTTP Headers
    start_response(status, headers)

    # The returned object is going to be printed
    return [b"Hello World"]

with make_server('', 8000, hello_world_app) as httpd:
    print("Serving on port 8000...")

    # Serve until process is killed
    httpd.serve_forever()
 Example of a WSGI application serving the current directory, accept optional directory and port number (default: 8000) on the command line: #!/usr/bin/env python3
'''
Small wsgiref based web server. Takes a path to serve from and an
optional port number (defaults to 8000), then tries to serve files.
Mime types are guessed from the file names, 404 errors are raised
if the file is not found. Used for the make serve target in Doc.
'''
import sys
import os
import mimetypes
from wsgiref import simple_server, util

def app(environ, respond):

    fn = os.path.join(path, environ['PATH_INFO'][1:])
    if '.' not in fn.split(os.path.sep)[-1]:
        fn = os.path.join(fn, 'index.html')
    type = mimetypes.guess_type(fn)[0]

    if os.path.exists(fn):
        respond('200 OK', [('Content-Type', type)])
        return util.FileWrapper(open(fn, "rb"))
    else:
        respond('404 Not Found', [('Content-Type', 'text/plain')])
        return [b'not found']

if __name__ == '__main__':
    path = sys.argv[1] if len(sys.argv) > 1 else os.getcwd()
    port = int(sys.argv[2]) if len(sys.argv) > 2 else 8000
    httpd = simple_server.make_server('', port, app)
    print("Serving {} on port {}, control-C to stop".format(path, port))
    try:
        httpd.serve_forever()
    except KeyboardInterrupt:
        print("Shutting down.")
        httpd.server_close()


class wsgiref.handlers.BaseCGIHandler(stdin, stdout, stderr, environ, multithread=True, multiprocess=False)
Similar to CGIHandler, but instead of using the sys and os modules, the CGI environment and I/O streams are specified explicitly. The multithread and multiprocess values are used to set the wsgi.multithread and wsgi.multiprocess flags for any applications run by the handler instance. This class is a subclass of SimpleHandler intended for use with software other than HTTP “origin servers”. If you are writing a gateway protocol implementation (such as CGI, FastCGI, SCGI, etc.) that uses a Status: header to send an HTTP status, you probably want to subclass this instead of SimpleHandler.


class wsgiref.handlers.BaseHandler
This is an abstract base class for running WSGI applications. Each instance will handle a single HTTP request, although in principle you could create a subclass that was reusable for multiple requests. BaseHandler instances have only one method intended for external use:
run(app)
Run the specified WSGI application, app.
 All of the other BaseHandler methods are invoked by this method in the process of running the application, and thus exist primarily to allow customizing the process. The following methods MUST be overridden in a subclass:
_write(data)
Buffer the bytes data for transmission to the client. It’s okay if this method actually transmits the data; BaseHandler just separates write and flush operations for greater efficiency when the underlying system actually has such a distinction.

_flush()
Force buffered data to be transmitted to the client. It’s okay if this method is a no-op (i.e., if _write() actually sends the data).

get_stdin()
Return an input stream object suitable for use as the wsgi.input of the request currently being processed.

get_stderr()
Return an output stream object suitable for use as the wsgi.errors of the request currently being processed.

add_cgi_vars()
Insert CGI variables for the current request into the environ attribute.
 Here are some other methods and attributes you may wish to override. This list is only a summary, however, and does not include every method that can be overridden. You should consult the docstrings and source code for additional information before attempting to create a customized BaseHandler subclass. Attributes and methods for customizing the WSGI environment:
wsgi_multithread
The value to be used for the wsgi.multithread environment variable. It defaults to true in BaseHandler, but may have a different default (or be set by the constructor) in the other subclasses.

wsgi_multiprocess
The value to be used for the wsgi.multiprocess environment variable. It defaults to true in BaseHandler, but may have a different default (or be set by the constructor) in the other subclasses.

wsgi_run_once
The value to be used for the wsgi.run_once environment variable. It defaults to false in BaseHandler, but CGIHandler sets it to true by default.

os_environ
The default environment variables to be included in every request’s WSGI environment. By default, this is a copy of os.environ at the time that wsgiref.handlers was imported, but subclasses can either create their own at the class or instance level. Note that the dictionary should be considered read-only, since the default value is shared between multiple classes and instances.

server_software
If the origin_server attribute is set, this attribute’s value is used to set the default SERVER_SOFTWARE WSGI environment variable, and also to set a default Server: header in HTTP responses. It is ignored for handlers (such as BaseCGIHandler and CGIHandler) that are not HTTP origin servers.  Changed in version 3.3: The term “Python” is replaced with implementation specific term like “CPython”, “Jython” etc.

get_scheme()
Return the URL scheme being used for the current request. The default implementation uses the guess_scheme() function from wsgiref.util to guess whether the scheme should be “http” or “https”, based on the current request’s environ variables.

setup_environ()
Set the environ attribute to a fully-populated WSGI environment. The default implementation uses all of the above methods and attributes, plus the get_stdin(), get_stderr(), and add_cgi_vars() methods and the wsgi_file_wrapper attribute. It also inserts a SERVER_SOFTWARE key if not present, as long as the origin_server attribute is a true value and the server_software attribute is set.
 Methods and attributes for customizing exception handling:
log_exception(exc_info)
Log the exc_info tuple in the server log. exc_info is a (type, value,
traceback) tuple. The default implementation simply writes the traceback to the request’s wsgi.errors stream and flushes it. Subclasses can override this method to change the format or retarget the output, mail the traceback to an administrator, or whatever other action may be deemed suitable.

traceback_limit
The maximum number of frames to include in tracebacks output by the default log_exception() method. If None, all frames are included.

error_output(environ, start_response)
This method is a WSGI application to generate an error page for the user. It is only invoked if an error occurs before headers are sent to the client. This method can access the current error information using sys.exc_info(), and should pass that information to start_response when calling it (as described in the “Error Handling” section of PEP 3333). The default implementation just uses the error_status, error_headers, and error_body attributes to generate an output page. Subclasses can override this to produce more dynamic error output. Note, however, that it’s not recommended from a security perspective to spit out diagnostics to any old user; ideally, you should have to do something special to enable diagnostic output, which is why the default implementation doesn’t include any.

error_status
The HTTP status used for error responses. This should be a status string as defined in PEP 3333; it defaults to a 500 code and message.

error_headers
The HTTP headers used for error responses. This should be a list of WSGI response headers ((name, value) tuples), as described in PEP 3333. The default list just sets the content type to text/plain.

error_body
The error response body. This should be an HTTP response body bytestring. It defaults to the plain text, “A server error occurred. Please contact the administrator.”
 Methods and attributes for PEP 3333’s “Optional Platform-Specific File Handling” feature:
wsgi_file_wrapper
A wsgi.file_wrapper factory, or None. The default value of this attribute is the wsgiref.util.FileWrapper class.

sendfile()
Override to implement platform-specific file transmission. This method is called only if the application’s return value is an instance of the class specified by the wsgi_file_wrapper attribute. It should return a true value if it was able to successfully transmit the file, so that the default transmission code will not be executed. The default implementation of this method just returns a false value.
 Miscellaneous methods and attributes:
origin_server
This attribute should be set to a true value if the handler’s _write() and _flush() are being used to communicate directly to the client, rather than via a CGI-like gateway protocol that wants the HTTP status in a special Status: header. This attribute’s default value is true in BaseHandler, but false in BaseCGIHandler and CGIHandler.

http_version
If origin_server is true, this string attribute is used to set the HTTP version of the response set to the client. It defaults to "1.0".


add_cgi_vars()
Insert CGI variables for the current request into the environ attribute.


error_body
The error response body. This should be an HTTP response body bytestring. It defaults to the plain text, “A server error occurred. Please contact the administrator.”


error_headers
The HTTP headers used for error responses. This should be a list of WSGI response headers ((name, value) tuples), as described in PEP 3333. The default list just sets the content type to text/plain.


error_output(environ, start_response)
This method is a WSGI application to generate an error page for the user. It is only invoked if an error occurs before headers are sent to the client. This method can access the current error information using sys.exc_info(), and should pass that information to start_response when calling it (as described in the “Error Handling” section of PEP 3333). The default implementation just uses the error_status, error_headers, and error_body attributes to generate an output page. Subclasses can override this to produce more dynamic error output. Note, however, that it’s not recommended from a security perspective to spit out diagnostics to any old user; ideally, you should have to do something special to enable diagnostic output, which is why the default implementation doesn’t include any.


error_status
The HTTP status used for error responses. This should be a status string as defined in PEP 3333; it defaults to a 500 code and message.


get_scheme()
Return the URL scheme being used for the current request. The default implementation uses the guess_scheme() function from wsgiref.util to guess whether the scheme should be “http” or “https”, based on the current request’s environ variables.


get_stderr()
Return an output stream object suitable for use as the wsgi.errors of the request currently being processed.


get_stdin()
Return an input stream object suitable for use as the wsgi.input of the request currently being processed.


http_version
If origin_server is true, this string attribute is used to set the HTTP version of the response set to the client. It defaults to "1.0".


log_exception(exc_info)
Log the exc_info tuple in the server log. exc_info is a (type, value,
traceback) tuple. The default implementation simply writes the traceback to the request’s wsgi.errors stream and flushes it. Subclasses can override this method to change the format or retarget the output, mail the traceback to an administrator, or whatever other action may be deemed suitable.


origin_server
This attribute should be set to a true value if the handler’s _write() and _flush() are being used to communicate directly to the client, rather than via a CGI-like gateway protocol that wants the HTTP status in a special Status: header. This attribute’s default value is true in BaseHandler, but false in BaseCGIHandler and CGIHandler.