| | """Utility code for constructing importers, etc.""" |
| | from ._abc import Loader |
| | from ._bootstrap import module_from_spec |
| | from ._bootstrap import _resolve_name |
| | from ._bootstrap import spec_from_loader |
| | from ._bootstrap import _find_spec |
| | from ._bootstrap_external import MAGIC_NUMBER |
| | from ._bootstrap_external import _RAW_MAGIC_NUMBER |
| | from ._bootstrap_external import cache_from_source |
| | from ._bootstrap_external import decode_source |
| | from ._bootstrap_external import source_from_cache |
| | from ._bootstrap_external import spec_from_file_location |
| |
|
| | from contextlib import contextmanager |
| | import _imp |
| | import functools |
| | import sys |
| | import types |
| | import warnings |
| |
|
| |
|
| | def source_hash(source_bytes): |
| | "Return the hash of *source_bytes* as used in hash-based pyc files." |
| | return _imp.source_hash(_RAW_MAGIC_NUMBER, source_bytes) |
| |
|
| |
|
| | def resolve_name(name, package): |
| | """Resolve a relative module name to an absolute one.""" |
| | if not name.startswith('.'): |
| | return name |
| | elif not package: |
| | raise ImportError(f'no package specified for {repr(name)} ' |
| | '(required for relative module names)') |
| | level = 0 |
| | for character in name: |
| | if character != '.': |
| | break |
| | level += 1 |
| | return _resolve_name(name[level:], package, level) |
| |
|
| |
|
| | def _find_spec_from_path(name, path=None): |
| | """Return the spec for the specified module. |
| | |
| | First, sys.modules is checked to see if the module was already imported. If |
| | so, then sys.modules[name].__spec__ is returned. If that happens to be |
| | set to None, then ValueError is raised. If the module is not in |
| | sys.modules, then sys.meta_path is searched for a suitable spec with the |
| | value of 'path' given to the finders. None is returned if no spec could |
| | be found. |
| | |
| | Dotted names do not have their parent packages implicitly imported. You will |
| | most likely need to explicitly import all parent packages in the proper |
| | order for a submodule to get the correct spec. |
| | |
| | """ |
| | if name not in sys.modules: |
| | return _find_spec(name, path) |
| | else: |
| | module = sys.modules[name] |
| | if module is None: |
| | return None |
| | try: |
| | spec = module.__spec__ |
| | except AttributeError: |
| | raise ValueError('{}.__spec__ is not set'.format(name)) from None |
| | else: |
| | if spec is None: |
| | raise ValueError('{}.__spec__ is None'.format(name)) |
| | return spec |
| |
|
| |
|
| | def find_spec(name, package=None): |
| | """Return the spec for the specified module. |
| | |
| | First, sys.modules is checked to see if the module was already imported. If |
| | so, then sys.modules[name].__spec__ is returned. If that happens to be |
| | set to None, then ValueError is raised. If the module is not in |
| | sys.modules, then sys.meta_path is searched for a suitable spec with the |
| | value of 'path' given to the finders. None is returned if no spec could |
| | be found. |
| | |
| | If the name is for submodule (contains a dot), the parent module is |
| | automatically imported. |
| | |
| | The name and package arguments work the same as importlib.import_module(). |
| | In other words, relative module names (with leading dots) work. |
| | |
| | """ |
| | fullname = resolve_name(name, package) if name.startswith('.') else name |
| | if fullname not in sys.modules: |
| | parent_name = fullname.rpartition('.')[0] |
| | if parent_name: |
| | parent = __import__(parent_name, fromlist=['__path__']) |
| | try: |
| | parent_path = parent.__path__ |
| | except AttributeError as e: |
| | raise ModuleNotFoundError( |
| | f"__path__ attribute not found on {parent_name!r} " |
| | f"while trying to find {fullname!r}", name=fullname) from e |
| | else: |
| | parent_path = None |
| | return _find_spec(fullname, parent_path) |
| | else: |
| | module = sys.modules[fullname] |
| | if module is None: |
| | return None |
| | try: |
| | spec = module.__spec__ |
| | except AttributeError: |
| | raise ValueError('{}.__spec__ is not set'.format(name)) from None |
| | else: |
| | if spec is None: |
| | raise ValueError('{}.__spec__ is None'.format(name)) |
| | return spec |
| |
|
| |
|
| | @contextmanager |
| | def _module_to_load(name): |
| | is_reload = name in sys.modules |
| |
|
| | module = sys.modules.get(name) |
| | if not is_reload: |
| | |
| | |
| | |
| | module = type(sys)(name) |
| | |
| | |
| | module.__initializing__ = True |
| | sys.modules[name] = module |
| | try: |
| | yield module |
| | except Exception: |
| | if not is_reload: |
| | try: |
| | del sys.modules[name] |
| | except KeyError: |
| | pass |
| | finally: |
| | module.__initializing__ = False |
| |
|
| |
|
| | def set_package(fxn): |
| | """Set __package__ on the returned module. |
| | |
| | This function is deprecated. |
| | |
| | """ |
| | @functools.wraps(fxn) |
| | def set_package_wrapper(*args, **kwargs): |
| | warnings.warn('The import system now takes care of this automatically; ' |
| | 'this decorator is slated for removal in Python 3.12', |
| | DeprecationWarning, stacklevel=2) |
| | module = fxn(*args, **kwargs) |
| | if getattr(module, '__package__', None) is None: |
| | module.__package__ = module.__name__ |
| | if not hasattr(module, '__path__'): |
| | module.__package__ = module.__package__.rpartition('.')[0] |
| | return module |
| | return set_package_wrapper |
| |
|
| |
|
| | def set_loader(fxn): |
| | """Set __loader__ on the returned module. |
| | |
| | This function is deprecated. |
| | |
| | """ |
| | @functools.wraps(fxn) |
| | def set_loader_wrapper(self, *args, **kwargs): |
| | warnings.warn('The import system now takes care of this automatically; ' |
| | 'this decorator is slated for removal in Python 3.12', |
| | DeprecationWarning, stacklevel=2) |
| | module = fxn(self, *args, **kwargs) |
| | if getattr(module, '__loader__', None) is None: |
| | module.__loader__ = self |
| | return module |
| | return set_loader_wrapper |
| |
|
| |
|
| | def module_for_loader(fxn): |
| | """Decorator to handle selecting the proper module for loaders. |
| | |
| | The decorated function is passed the module to use instead of the module |
| | name. The module passed in to the function is either from sys.modules if |
| | it already exists or is a new module. If the module is new, then __name__ |
| | is set the first argument to the method, __loader__ is set to self, and |
| | __package__ is set accordingly (if self.is_package() is defined) will be set |
| | before it is passed to the decorated function (if self.is_package() does |
| | not work for the module it will be set post-load). |
| | |
| | If an exception is raised and the decorator created the module it is |
| | subsequently removed from sys.modules. |
| | |
| | The decorator assumes that the decorated function takes the module name as |
| | the second argument. |
| | |
| | """ |
| | warnings.warn('The import system now takes care of this automatically; ' |
| | 'this decorator is slated for removal in Python 3.12', |
| | DeprecationWarning, stacklevel=2) |
| | @functools.wraps(fxn) |
| | def module_for_loader_wrapper(self, fullname, *args, **kwargs): |
| | with _module_to_load(fullname) as module: |
| | module.__loader__ = self |
| | try: |
| | is_package = self.is_package(fullname) |
| | except (ImportError, AttributeError): |
| | pass |
| | else: |
| | if is_package: |
| | module.__package__ = fullname |
| | else: |
| | module.__package__ = fullname.rpartition('.')[0] |
| | |
| | return fxn(self, module, *args, **kwargs) |
| |
|
| | return module_for_loader_wrapper |
| |
|
| |
|
| | class _LazyModule(types.ModuleType): |
| |
|
| | """A subclass of the module type which triggers loading upon attribute access.""" |
| |
|
| | def __getattribute__(self, attr): |
| | """Trigger the load of the module and return the attribute.""" |
| | |
| | |
| | |
| | self.__class__ = types.ModuleType |
| | |
| | |
| | original_name = self.__spec__.name |
| | |
| | |
| | attrs_then = self.__spec__.loader_state['__dict__'] |
| | attrs_now = self.__dict__ |
| | attrs_updated = {} |
| | for key, value in attrs_now.items(): |
| | |
| | |
| | if key not in attrs_then: |
| | attrs_updated[key] = value |
| | elif id(attrs_now[key]) != id(attrs_then[key]): |
| | attrs_updated[key] = value |
| | self.__spec__.loader.exec_module(self) |
| | |
| | |
| | if original_name in sys.modules: |
| | if id(self) != id(sys.modules[original_name]): |
| | raise ValueError(f"module object for {original_name!r} " |
| | "substituted in sys.modules during a lazy " |
| | "load") |
| | |
| | |
| | self.__dict__.update(attrs_updated) |
| | return getattr(self, attr) |
| |
|
| | def __delattr__(self, attr): |
| | """Trigger the load and then perform the deletion.""" |
| | |
| | |
| | self.__getattribute__(attr) |
| | delattr(self, attr) |
| |
|
| |
|
| | class LazyLoader(Loader): |
| |
|
| | """A loader that creates a module which defers loading until attribute access.""" |
| |
|
| | @staticmethod |
| | def __check_eager_loader(loader): |
| | if not hasattr(loader, 'exec_module'): |
| | raise TypeError('loader must define exec_module()') |
| |
|
| | @classmethod |
| | def factory(cls, loader): |
| | """Construct a callable which returns the eager loader made lazy.""" |
| | cls.__check_eager_loader(loader) |
| | return lambda *args, **kwargs: cls(loader(*args, **kwargs)) |
| |
|
| | def __init__(self, loader): |
| | self.__check_eager_loader(loader) |
| | self.loader = loader |
| |
|
| | def create_module(self, spec): |
| | return self.loader.create_module(spec) |
| |
|
| | def exec_module(self, module): |
| | """Make the module load lazily.""" |
| | module.__spec__.loader = self.loader |
| | module.__loader__ = self.loader |
| | |
| | |
| | |
| | |
| | loader_state = {} |
| | loader_state['__dict__'] = module.__dict__.copy() |
| | loader_state['__class__'] = module.__class__ |
| | module.__spec__.loader_state = loader_state |
| | module.__class__ = _LazyModule |
| |
|