Repository: cython/cython

Issue:
[BUG] pyximport uses deprecated "imp" module
Replace it with `importlib` or whatever seems appropriate and modern.


Discussion:
I was looking into the problem and pyximport uses more deprecated components - e.g. we are implementing find_module hook which is deprecated from 3.10 [1]. Since we still need do compatibility magic (`importlib` cannot be used in python 2.7), maybe it will be easier to total refactor of pyximport rather than trying to fit `importlib` to old way of importing. (We will keep old pyximport for 2.7 support)

[1] https://docs.python.org/3/library/importlib.html#importlib.abc.Finder.find_module
>total refactor of pyximport rather than trying to fit `importlib` to
>old way of importing. (We will keep old pyximport for 2.7 support)

Sounds good to me. We could have a _pyximport2 and a fresh _pyximport3 module, and then have pyximport itself only import the right one. We would drop the ...2 version in Cython 3.1 then, and stick with the clean new module. So that's a good preparation.


Resolving patch:
diff --git a/pyximport/_pyximport2.py b/pyximport/_pyximport2.py
new file mode 100644
--- /dev/null
+++ b/pyximport/_pyximport2.py
@@ -0,0 +1,606 @@
+"""
+Import hooks; when installed with the install() function, these hooks
+allow importing .pyx files as if they were Python modules.
+
+If you want the hook installed every time you run Python
+you can add it to your Python version by adding these lines to
+sitecustomize.py (which you can create from scratch in site-packages
+if it doesn't exist there or somewhere else on your python path)::
+
+    import pyximport
+    pyximport.install()
+
+For instance on the Mac with a non-system Python 2.3, you could create
+sitecustomize.py with only those two lines at
+/usr/local/lib/python2.3/site-packages/sitecustomize.py .
+
+A custom distutils.core.Extension instance and setup() args
+(Distribution) for for the build can be defined by a <modulename>.pyxbld
+file like:
+
+# examplemod.pyxbld
+def make_ext(modname, pyxfilename):
+    from distutils.extension import Extension
+    return Extension(name = modname,
+                     sources=[pyxfilename, 'hello.c'],
+                     include_dirs=['/myinclude'] )
+def make_setup_args():
+    return dict(script_args=["--compiler=mingw32"])
+
+Extra dependencies can be defined by a <modulename>.pyxdep .
+See README.
+
+Since Cython 0.11, the :mod:`pyximport` module also has experimental
+compilation support for normal Python modules.  This allows you to
+automatically run Cython on every .pyx and .py module that Python
+imports, including parts of the standard library and installed
+packages.  Cython will still fail to compile a lot of Python modules,
+in which case the import mechanism will fall back to loading the
+Python source modules instead.  The .py import mechanism is installed
+like this::
+
+    pyximport.install(pyimport = True)
+
+Running this module as a top-level script will run a test and then print
+the documentation.
+
+This code is based on the Py2.3+ import protocol as described in PEP 302.
+"""
+
+import glob
+import imp
+import os
+import sys
+from zipimport import zipimporter, ZipImportError
+
+mod_name = "pyximport"
+
+PYX_EXT = ".pyx"
+PYXDEP_EXT = ".pyxdep"
+PYXBLD_EXT = ".pyxbld"
+
+DEBUG_IMPORT = False
+
+
+def _print(message, args):
+    if args:
+        message = message % args
+    print(message)
+
+
+def _debug(message, *args):
+    if DEBUG_IMPORT:
+        _print(message, args)
+
+
+def _info(message, *args):
+    _print(message, args)
+
+
+# Performance problem: for every PYX file that is imported, we will
+# invoke the whole distutils infrastructure even if the module is
+# already built. It might be more efficient to only do it when the
+# mod time of the .pyx is newer than the mod time of the .so but
+# the question is how to get distutils to tell me the name of the .so
+# before it builds it. Maybe it is easy...but maybe the performance
+# issue isn't real.
+def _load_pyrex(name, filename):
+    "Load a pyrex file given a name and filename."
+
+
+def get_distutils_extension(modname, pyxfilename, language_level=None):
+#    try:
+#        import hashlib
+#    except ImportError:
+#        import md5 as hashlib
+#    extra = "_" + hashlib.md5(open(pyxfilename).read()).hexdigest()
+#    modname = modname + extra
+    extension_mod,setup_args = handle_special_build(modname, pyxfilename)
+    if not extension_mod:
+        if not isinstance(pyxfilename, str):
+            # distutils is stupid in Py2 and requires exactly 'str'
+            # => encode accidentally coerced unicode strings back to str
+            pyxfilename = pyxfilename.encode(sys.getfilesystemencoding())
+        from distutils.extension import Extension
+        extension_mod = Extension(name = modname, sources=[pyxfilename])
+        if language_level is not None:
+            extension_mod.cython_directives = {'language_level': language_level}
+    return extension_mod,setup_args
+
+
+def handle_special_build(modname, pyxfilename):
+    special_build = os.path.splitext(pyxfilename)[0] + PYXBLD_EXT
+    ext = None
+    setup_args={}
+    if os.path.exists(special_build):
+        # globls = {}
+        # locs = {}
+        # execfile(special_build, globls, locs)
+        # ext = locs["make_ext"](modname, pyxfilename)
+        with open(special_build) as fid:
+            mod = imp.load_source("XXXX", special_build, fid)
+        make_ext = getattr(mod,'make_ext',None)
+        if make_ext:
+            ext = make_ext(modname, pyxfilename)
+            assert ext and ext.sources, "make_ext in %s did not return Extension" % special_build
+        make_setup_args = getattr(mod, 'make_setup_args',None)
+        if make_setup_args:
+            setup_args = make_setup_args()
+            assert isinstance(setup_args,dict), ("make_setup_args in %s did not return a dict"
+                                         % special_build)
+        assert set or setup_args, ("neither make_ext nor make_setup_args %s"
+                                         % special_build)
+        ext.sources = [os.path.join(os.path.dirname(special_build), source)
+                       for source in ext.sources]
+    return ext, setup_args
+
+
+def handle_dependencies(pyxfilename):
+    testing = '_test_files' in globals()
+    dependfile = os.path.splitext(pyxfilename)[0] + PYXDEP_EXT
+
+    # by default let distutils decide whether to rebuild on its own
+    # (it has a better idea of what the output file will be)
+
+    # but we know more about dependencies so force a rebuild if
+    # some of the dependencies are newer than the pyxfile.
+    if os.path.exists(dependfile):
+        with open(dependfile) as fid:
+            depends = fid.readlines()
+        depends = [depend.strip() for depend in depends]
+
+        # gather dependencies in the "files" variable
+        # the dependency file is itself a dependency
+        files = [dependfile]
+        for depend in depends:
+            fullpath = os.path.join(os.path.dirname(dependfile),
+                                    depend)
+            files.extend(glob.glob(fullpath))
+
+        # only for unit testing to see we did the right thing
+        if testing:
+            _test_files[:] = []  #$pycheck_no
+
+        # if any file that the pyxfile depends upon is newer than
+        # the pyx file, 'touch' the pyx file so that distutils will
+        # be tricked into rebuilding it.
+        for file in files:
+            from distutils.dep_util import newer
+            if newer(file, pyxfilename):
+                _debug("Rebuilding %s because of %s", pyxfilename, file)
+                filetime = os.path.getmtime(file)
+                os.utime(pyxfilename, (filetime, filetime))
+                if testing:
+                    _test_files.append(file)
+
+
+def build_module(name, pyxfilename, pyxbuild_dir=None, inplace=False, language_level=None):
+    assert os.path.exists(pyxfilename), "Path does not exist: %s" % pyxfilename
+    handle_dependencies(pyxfilename)
+
+    extension_mod, setup_args = get_distutils_extension(name, pyxfilename, language_level)
+    build_in_temp = pyxargs.build_in_temp
+    sargs = pyxargs.setup_args.copy()
+    sargs.update(setup_args)
+    build_in_temp = sargs.pop('build_in_temp',build_in_temp)
+
+    from . import pyxbuild
+    so_path = pyxbuild.pyx_to_dll(pyxfilename, extension_mod,
+                                  build_in_temp=build_in_temp,
+                                  pyxbuild_dir=pyxbuild_dir,
+                                  setup_args=sargs,
+                                  inplace=inplace,
+                                  reload_support=pyxargs.reload_support)
+    assert os.path.exists(so_path), "Cannot find: %s" % so_path
+
+    junkpath = os.path.join(os.path.dirname(so_path), name+"_*")  #very dangerous with --inplace ? yes, indeed, trying to eat my files ;)
+    junkstuff = glob.glob(junkpath)
+    for path in junkstuff:
+        if path != so_path:
+            try:
+                os.remove(path)
+            except IOError:
+                _info("Couldn't remove %s", path)
+
+    return so_path
+
+
+def load_module(name, pyxfilename, pyxbuild_dir=None, is_package=False,
+                build_inplace=False, language_level=None, so_path=None):
+    try:
+        if so_path is None:
+            if is_package:
+                module_name = name + '.__init__'
+            else:
+                module_name = name
+            so_path = build_module(module_name, pyxfilename, pyxbuild_dir,
+                                   inplace=build_inplace, language_level=language_level)
+        mod = imp.load_dynamic(name, so_path)
+        if is_package and not hasattr(mod, '__path__'):
+            mod.__path__ = [os.path.dirname(so_path)]
+        assert mod.__file__ == so_path, (mod.__file__, so_path)
+    except Exception as failure_exc:
+        _debug("Failed to load extension module: %r" % failure_exc)
+        if pyxargs.load_py_module_on_import_failure and pyxfilename.endswith('.py'):
+            # try to fall back to normal import
+            mod = imp.load_source(name, pyxfilename)
+            assert mod.__file__ in (pyxfilename, pyxfilename+'c', pyxfilename+'o'), (mod.__file__, pyxfilename)
+        else:
+            tb = sys.exc_info()[2]
+            import traceback
+            exc = ImportError("Building module %s failed: %s" % (
+                name, traceback.format_exception_only(*sys.exc_info()[:2])))
+            if sys.version_info[0] >= 3:
+                raise exc.with_traceback(tb)
+            else:
+                exec("raise exc, None, tb", {'exc': exc, 'tb': tb})
+    return mod
+
+
+# import hooks
+
+class PyxImporter(object):
+    """A meta-path importer for .pyx files.
+    """
+    def __init__(self, extension=PYX_EXT, pyxbuild_dir=None, inplace=False,
+                 language_level=None):
+        self.extension = extension
+        self.pyxbuild_dir = pyxbuild_dir
+        self.inplace = inplace
+        self.language_level = language_level
+
+    def find_module(self, fullname, package_path=None):
+        if fullname in sys.modules  and  not pyxargs.reload_support:
+            return None  # only here when reload()
+
+        # package_path might be a _NamespacePath. Convert that into a list...
+        if package_path is not None and not isinstance(package_path, list):
+            package_path = list(package_path)
+        try:
+            fp, pathname, (ext,mode,ty) = imp.find_module(fullname,package_path)
+            if fp: fp.close()  # Python should offer a Default-Loader to avoid this double find/open!
+            if pathname and ty == imp.PKG_DIRECTORY:
+                pkg_file = os.path.join(pathname, '__init__'+self.extension)
+                if os.path.isfile(pkg_file):
+                    return PyxLoader(fullname, pathname,
+                        init_path=pkg_file,
+                        pyxbuild_dir=self.pyxbuild_dir,
+                        inplace=self.inplace,
+                        language_level=self.language_level)
+            if pathname and pathname.endswith(self.extension):
+                return PyxLoader(fullname, pathname,
+                                 pyxbuild_dir=self.pyxbuild_dir,
+                                 inplace=self.inplace,
+                                 language_level=self.language_level)
+            if ty != imp.C_EXTENSION:  # only when an extension, check if we have a .pyx next!
+                return None
+
+            # find .pyx fast, when .so/.pyd exist --inplace
+            pyxpath = os.path.splitext(pathname)[0]+self.extension
+            if os.path.isfile(pyxpath):
+                return PyxLoader(fullname, pyxpath,
+                                 pyxbuild_dir=self.pyxbuild_dir,
+                                 inplace=self.inplace,
+                                 language_level=self.language_level)
+
+            # .so/.pyd's on PATH should not be remote from .pyx's
+            # think no need to implement PyxArgs.importer_search_remote here?
+
+        except ImportError:
+            pass
+
+        # searching sys.path ...
+
+        #if DEBUG_IMPORT:  print "SEARCHING", fullname, package_path
+
+        mod_parts = fullname.split('.')
+        module_name = mod_parts[-1]
+        pyx_module_name = module_name + self.extension
+
+        # this may work, but it returns the file content, not its path
+        #import pkgutil
+        #pyx_source = pkgutil.get_data(package, pyx_module_name)
+
+        paths = package_path or sys.path
+        for path in paths:
+            pyx_data = None
+            if not path:
+                path = os.getcwd()
+            elif os.path.isfile(path):
+                try:
+                    zi = zipimporter(path)
+                    pyx_data = zi.get_data(pyx_module_name)
+                except (ZipImportError, IOError, OSError):
+                    continue  # Module not found.
+                # unzip the imported file into the build dir
+                # FIXME: can interfere with later imports if build dir is in sys.path and comes before zip file
+                path = self.pyxbuild_dir
+            elif not os.path.isabs(path):
+                path = os.path.abspath(path)
+
+            pyx_module_path = os.path.join(path, pyx_module_name)
+            if pyx_data is not None:
+                if not os.path.exists(path):
+                    try:
+                        os.makedirs(path)
+                    except OSError:
+                        # concurrency issue?
+                        if not os.path.exists(path):
+                            raise
+                with open(pyx_module_path, "wb") as f:
+                    f.write(pyx_data)
+            elif not os.path.isfile(pyx_module_path):
+                continue  # Module not found.
+
+            return PyxLoader(fullname, pyx_module_path,
+                             pyxbuild_dir=self.pyxbuild_dir,
+                             inplace=self.inplace,
+                             language_level=self.language_level)
+
+        # not found, normal package, not a .pyx file, none of our business
+        _debug("%s not found" % fullname)
+        return None
+
+
+class PyImporter(PyxImporter):
+    """A meta-path importer for normal .py files.
+    """
+    def __init__(self, pyxbuild_dir=None, inplace=False, language_level=None):
+        if language_level is None:
+            language_level = sys.version_info[0]
+        self.super = super(PyImporter, self)
+        self.super.__init__(extension='.py', pyxbuild_dir=pyxbuild_dir, inplace=inplace,
+                            language_level=language_level)
+        self.uncompilable_modules = {}
+        self.blocked_modules = ['Cython', 'pyxbuild', 'pyximport.pyxbuild',
+                                'distutils']
+        self.blocked_packages = ['Cython.', 'distutils.']
+
+    def find_module(self, fullname, package_path=None):
+        if fullname in sys.modules:
+            return None
+        if any([fullname.startswith(pkg) for pkg in self.blocked_packages]):
+            return None
+        if fullname in self.blocked_modules:
+            # prevent infinite recursion
+            return None
+        if _lib_loader.knows(fullname):
+            return _lib_loader
+        _debug("trying import of module '%s'", fullname)
+        if fullname in self.uncompilable_modules:
+            path, last_modified = self.uncompilable_modules[fullname]
+            try:
+                new_last_modified = os.stat(path).st_mtime
+                if new_last_modified > last_modified:
+                    # import would fail again
+                    return None
+            except OSError:
+                # module is no longer where we found it, retry the import
+                pass
+
+        self.blocked_modules.append(fullname)
+        try:
+            importer = self.super.find_module(fullname, package_path)
+            if importer is not None:
+                if importer.init_path:
+                    path = importer.init_path
+                    real_name = fullname + '.__init__'
+                else:
+                    path = importer.path
+                    real_name = fullname
+                _debug("importer found path %s for module %s", path, real_name)
+                try:
+                    so_path = build_module(
+                        real_name, path,
+                        pyxbuild_dir=self.pyxbuild_dir,
+                        language_level=self.language_level,
+                        inplace=self.inplace)
+                    _lib_loader.add_lib(fullname, path, so_path,
+                                        is_package=bool(importer.init_path))
+                    return _lib_loader
+                except Exception:
+                    if DEBUG_IMPORT:
+                        import traceback
+                        traceback.print_exc()
+                    # build failed, not a compilable Python module
+                    try:
+                        last_modified = os.stat(path).st_mtime
+                    except OSError:
+                        last_modified = 0
+                    self.uncompilable_modules[fullname] = (path, last_modified)
+                    importer = None
+        finally:
+            self.blocked_modules.pop()
+        return importer
+
+
+class LibLoader(object):
+    def __init__(self):
+        self._libs = {}
+
+    def load_module(self, fullname):
+        try:
+            source_path, so_path, is_package = self._libs[fullname]
+        except KeyError:
+            raise ValueError("invalid module %s" % fullname)
+        _debug("Loading shared library module '%s' from %s", fullname, so_path)
+        return load_module(fullname, source_path, so_path=so_path, is_package=is_package)
+
+    def add_lib(self, fullname, path, so_path, is_package):
+        self._libs[fullname] = (path, so_path, is_package)
+
+    def knows(self, fullname):
+        return fullname in self._libs
+
+_lib_loader = LibLoader()
+
+
+class PyxLoader(object):
+    def __init__(self, fullname, path, init_path=None, pyxbuild_dir=None,
+                 inplace=False, language_level=None):
+        _debug("PyxLoader created for loading %s from %s (init path: %s)",
+               fullname, path, init_path)
+        self.fullname = fullname
+        self.path, self.init_path = path, init_path
+        self.pyxbuild_dir = pyxbuild_dir
+        self.inplace = inplace
+        self.language_level = language_level
+
+    def load_module(self, fullname):
+        assert self.fullname == fullname, (
+            "invalid module, expected %s, got %s" % (
+            self.fullname, fullname))
+        if self.init_path:
+            # package
+            #print "PACKAGE", fullname
+            module = load_module(fullname, self.init_path,
+                                 self.pyxbuild_dir, is_package=True,
+                                 build_inplace=self.inplace,
+                                 language_level=self.language_level)
+            module.__path__ = [self.path]
+        else:
+            #print "MODULE", fullname
+            module = load_module(fullname, self.path,
+                                 self.pyxbuild_dir,
+                                 build_inplace=self.inplace,
+                                 language_level=self.language_level)
+        return module
+
+
+#install args
+class PyxArgs(object):
+    build_dir=True
+    build_in_temp=True
+    setup_args={}   #None
+
+##pyxargs=None
+
+
+def _have_importers():
+    has_py_importer = False
+    has_pyx_importer = False
+    for importer in sys.meta_path:
+        if isinstance(importer, PyxImporter):
+            if isinstance(importer, PyImporter):
+                has_py_importer = True
+            else:
+                has_pyx_importer = True
+
+    return has_py_importer, has_pyx_importer
+
+
+def install(pyximport=True, pyimport=False, build_dir=None, build_in_temp=True,
+            setup_args=None, reload_support=False,
+            load_py_module_on_import_failure=False, inplace=False,
+            language_level=None):
+    """ Main entry point for pyxinstall.
+
+    Call this to install the ``.pyx`` import hook in
+    your meta-path for a single Python process.  If you want it to be
+    installed whenever you use Python, add it to your ``sitecustomize``
+    (as described above).
+
+    :param pyximport: If set to False, does not try to import ``.pyx`` files.
+
+    :param pyimport: You can pass ``pyimport=True`` to also
+        install the ``.py`` import hook
+        in your meta-path.  Note, however, that it is rather experimental,
+        will not work at all for some ``.py`` files and packages, and will
+        heavily slow down your imports due to search and compilation.
+        Use at your own risk.
+
+    :param build_dir: By default, compiled modules will end up in a ``.pyxbld``
+        directory in the user's home directory.  Passing a different path
+        as ``build_dir`` will override this.
+
+    :param build_in_temp: If ``False``, will produce the C files locally. Working
+        with complex dependencies and debugging becomes more easy. This
+        can principally interfere with existing files of the same name.
+
+    :param setup_args: Dict of arguments for Distribution.
+        See ``distutils.core.setup()``.
+
+    :param reload_support: Enables support for dynamic
+        ``reload(my_module)``, e.g. after a change in the Cython code.
+        Additional files ``<so_path>.reloadNN`` may arise on that account, when
+        the previously loaded module file cannot be overwritten.
+
+    :param load_py_module_on_import_failure: If the compilation of a ``.py``
+        file succeeds, but the subsequent import fails for some reason,
+        retry the import with the normal ``.py`` module instead of the
+        compiled module.  Note that this may lead to unpredictable results
+        for modules that change the system state during their import, as
+        the second import will rerun these modifications in whatever state
+        the system was left after the import of the compiled module
+        failed.
+
+    :param inplace: Install the compiled module
+        (``.so`` for Linux and Mac / ``.pyd`` for Windows)
+        next to the source file.
+
+    :param language_level: The source language level to use: 2 or 3.
+        The default is to use the language level of the current Python
+        runtime for .py files and Py2 for ``.pyx`` files.
+    """
+    if setup_args is None:
+        setup_args = {}
+    if not build_dir:
+        build_dir = os.path.join(os.path.expanduser('~'), '.pyxbld')
+
+    global pyxargs
+    pyxargs = PyxArgs()  #$pycheck_no
+    pyxargs.build_dir = build_dir
+    pyxargs.build_in_temp = build_in_temp
+    pyxargs.setup_args = (setup_args or {}).copy()
+    pyxargs.reload_support = reload_support
+    pyxargs.load_py_module_on_import_failure = load_py_module_on_import_failure
+
+    has_py_importer, has_pyx_importer = _have_importers()
+    py_importer, pyx_importer = None, None
+
+    if pyimport and not has_py_importer:
+        py_importer = PyImporter(pyxbuild_dir=build_dir, inplace=inplace,
+                                 language_level=language_level)
+        # make sure we import Cython before we install the import hook
+        import Cython.Compiler.Main, Cython.Compiler.Pipeline, Cython.Compiler.Optimize
+        sys.meta_path.insert(0, py_importer)
+
+    if pyximport and not has_pyx_importer:
+        pyx_importer = PyxImporter(pyxbuild_dir=build_dir, inplace=inplace,
+                                   language_level=language_level)
+        sys.meta_path.append(pyx_importer)
+
+    return py_importer, pyx_importer
+
+
+def uninstall(py_importer, pyx_importer):
+    """
+    Uninstall an import hook.
+    """
+    try:
+        sys.meta_path.remove(py_importer)
+    except ValueError:
+        pass
+
+    try:
+        sys.meta_path.remove(pyx_importer)
+    except ValueError:
+        pass
+
+
+# MAIN
+
+def show_docs():
+    import __main__
+    __main__.__name__ = mod_name
+    for name in dir(__main__):
+        item = getattr(__main__, name)
+        try:
+            setattr(item, "__module__", mod_name)
+        except (AttributeError, TypeError):
+            pass
+    help(__main__)
+
+
+if __name__ == '__main__':
+    show_docs()
diff --git a/pyximport/_pyximport3.py b/pyximport/_pyximport3.py
new file mode 100644
--- /dev/null
+++ b/pyximport/_pyximport3.py
@@ -0,0 +1,464 @@
+"""
+Import hooks; when installed with the install() function, these hooks
+allow importing .pyx files as if they were Python modules.
+
+If you want the hook installed every time you run Python
+you can add it to your Python version by adding these lines to
+sitecustomize.py (which you can create from scratch in site-packages
+if it doesn't exist there or somewhere else on your python path)::
+
+    import pyximport
+    pyximport.install()
+
+For instance on the Mac with a non-system Python 2.3, you could create
+sitecustomize.py with only those two lines at
+/usr/local/lib/python2.3/site-packages/sitecustomize.py .
+
+A custom distutils.core.Extension instance and setup() args
+(Distribution) for for the build can be defined by a <modulename>.pyxbld
+file like:
+
+# examplemod.pyxbld
+def make_ext(modname, pyxfilename):
+    from distutils.extension import Extension
+    return Extension(name = modname,
+                     sources=[pyxfilename, 'hello.c'],
+                     include_dirs=['/myinclude'] )
+def make_setup_args():
+    return dict(script_args=["--compiler=mingw32"])
+
+Extra dependencies can be defined by a <modulename>.pyxdep .
+See README.
+
+Since Cython 0.11, the :mod:`pyximport` module also has experimental
+compilation support for normal Python modules.  This allows you to
+automatically run Cython on every .pyx and .py module that Python
+imports, including parts of the standard library and installed
+packages.  Cython will still fail to compile a lot of Python modules,
+in which case the import mechanism will fall back to loading the
+Python source modules instead.  The .py import mechanism is installed
+like this::
+
+    pyximport.install(pyimport = True)
+
+Running this module as a top-level script will run a test and then print
+the documentation.
+"""
+
+import glob
+import importlib
+import os
+import sys
+from importlib.abc import MetaPathFinder
+from importlib.machinery import ExtensionFileLoader, SourceFileLoader
+from importlib.util import spec_from_file_location
+
+mod_name = "pyximport"
+
+PY_EXT = ".py"
+PYX_EXT = ".pyx"
+PYXDEP_EXT = ".pyxdep"
+PYXBLD_EXT = ".pyxbld"
+
+DEBUG_IMPORT = False
+
+
+def _print(message, args):
+    if args:
+        message = message % args
+    print(message)
+
+
+def _debug(message, *args):
+    if DEBUG_IMPORT:
+        _print(message, args)
+
+
+def _info(message, *args):
+    _print(message, args)
+
+
+def load_source(file_path):
+    import importlib.util
+    from importlib.machinery import SourceFileLoader
+    spec = importlib.util.spec_from_file_location("XXXX", file_path, loader=SourceFileLoader("XXXX", file_path))
+    module = importlib.util.module_from_spec(spec)
+    spec.loader.exec_module(module)
+    return module
+
+
+def get_distutils_extension(modname, pyxfilename, language_level=None):
+#    try:
+#        import hashlib
+#    except ImportError:
+#        import md5 as hashlib
+#    extra = "_" + hashlib.md5(open(pyxfilename).read()).hexdigest()
+#    modname = modname + extra
+    extension_mod,setup_args = handle_special_build(modname, pyxfilename)
+    if not extension_mod:
+        if not isinstance(pyxfilename, str):
+            # distutils is stupid in Py2 and requires exactly 'str'
+            # => encode accidentally coerced unicode strings back to str
+            pyxfilename = pyxfilename.encode(sys.getfilesystemencoding())
+        from distutils.extension import Extension
+        extension_mod = Extension(name = modname, sources=[pyxfilename])
+        if language_level is not None:
+            extension_mod.cython_directives = {'language_level': language_level}
+    return extension_mod,setup_args
+
+
+def handle_special_build(modname, pyxfilename):
+    special_build = os.path.splitext(pyxfilename)[0] + PYXBLD_EXT
+    ext = None
+    setup_args={}
+    if os.path.exists(special_build):
+        # globls = {}
+        # locs = {}
+        # execfile(special_build, globls, locs)
+        # ext = locs["make_ext"](modname, pyxfilename)
+        mod = load_source(special_build)
+        make_ext = getattr(mod,'make_ext',None)
+        if make_ext:
+            ext = make_ext(modname, pyxfilename)
+            assert ext and ext.sources, "make_ext in %s did not return Extension" % special_build
+        make_setup_args = getattr(mod, 'make_setup_args',None)
+        if make_setup_args:
+            setup_args = make_setup_args()
+            assert isinstance(setup_args,dict), ("make_setup_args in %s did not return a dict"
+                                         % special_build)
+        assert set or setup_args, ("neither make_ext nor make_setup_args %s"
+                                         % special_build)
+        ext.sources = [os.path.join(os.path.dirname(special_build), source)
+                       for source in ext.sources]
+    return ext, setup_args
+
+
+def handle_dependencies(pyxfilename):
+    testing = '_test_files' in globals()
+    dependfile = os.path.splitext(pyxfilename)[0] + PYXDEP_EXT
+
+    # by default let distutils decide whether to rebuild on its own
+    # (it has a better idea of what the output file will be)
+
+    # but we know more about dependencies so force a rebuild if
+    # some of the dependencies are newer than the pyxfile.
+    if os.path.exists(dependfile):
+        with open(dependfile) as fid:
+            depends = fid.readlines()
+        depends = [depend.strip() for depend in depends]
+
+        # gather dependencies in the "files" variable
+        # the dependency file is itself a dependency
+        files = [dependfile]
+        for depend in depends:
+            fullpath = os.path.join(os.path.dirname(dependfile),
+                                    depend)
+            files.extend(glob.glob(fullpath))
+
+        # only for unit testing to see we did the right thing
+        if testing:
+            _test_files[:] = []  #$pycheck_no
+
+        # if any file that the pyxfile depends upon is newer than
+        # the pyx file, 'touch' the pyx file so that distutils will
+        # be tricked into rebuilding it.
+        for file in files:
+            from distutils.dep_util import newer
+            if newer(file, pyxfilename):
+                _debug("Rebuilding %s because of %s", pyxfilename, file)
+                filetime = os.path.getmtime(file)
+                os.utime(pyxfilename, (filetime, filetime))
+                if testing:
+                    _test_files.append(file)
+
+
+def build_module(name, pyxfilename, pyxbuild_dir=None, inplace=False, language_level=None):
+    assert os.path.exists(pyxfilename), "Path does not exist: %s" % pyxfilename
+    handle_dependencies(pyxfilename)
+
+    extension_mod, setup_args = get_distutils_extension(name, pyxfilename, language_level)
+    build_in_temp = pyxargs.build_in_temp
+    sargs = pyxargs.setup_args.copy()
+    sargs.update(setup_args)
+    build_in_temp = sargs.pop('build_in_temp',build_in_temp)
+
+    from . import pyxbuild
+    so_path = pyxbuild.pyx_to_dll(pyxfilename, extension_mod,
+                                  build_in_temp=build_in_temp,
+                                  pyxbuild_dir=pyxbuild_dir,
+                                  setup_args=sargs,
+                                  inplace=inplace,
+                                  reload_support=pyxargs.reload_support)
+    assert os.path.exists(so_path), "Cannot find: %s" % so_path
+
+    junkpath = os.path.join(os.path.dirname(so_path), name+"_*")  #very dangerous with --inplace ? yes, indeed, trying to eat my files ;)
+    junkstuff = glob.glob(junkpath)
+    for path in junkstuff:
+        if path != so_path:
+            try:
+                os.remove(path)
+            except IOError:
+                _info("Couldn't remove %s", path)
+
+    return so_path
+
+
+# import hooks
+
+class PyxImportMetaFinder(MetaPathFinder):
+
+    def __init__(self, extension=PYX_EXT, pyxbuild_dir=None, inplace=False, language_level=None):
+        self.pyxbuild_dir = pyxbuild_dir
+        self.inplace = inplace
+        self.language_level = language_level
+        self.extension = extension
+
+    def find_spec(self, fullname, path, target=None):
+        if not path:
+            path = [os.getcwd()]  # top level import --
+        if "." in fullname:
+            *parents, name = fullname.split(".")
+        else:
+            name = fullname
+        for entry in path:
+            if os.path.isdir(os.path.join(entry, name)):
+                # this module has child modules
+                filename = os.path.join(entry, name, "__init__" + self.extension)
+                submodule_locations = [os.path.join(entry, name)]
+            else:
+                filename = os.path.join(entry, name + self.extension)
+                submodule_locations = None
+            if not os.path.exists(filename):
+                continue
+
+            return spec_from_file_location(
+                fullname, filename,
+                loader=PyxImportLoader(filename, self.pyxbuild_dir, self.inplace, self.language_level),
+                submodule_search_locations=submodule_locations)
+
+        return None  # we don't know how to import this
+
+
+class PyImportMetaFinder(MetaPathFinder):
+
+    def __init__(self, extension=PY_EXT, pyxbuild_dir=None, inplace=False, language_level=None):
+        self.pyxbuild_dir = pyxbuild_dir
+        self.inplace = inplace
+        self.language_level = language_level
+        self.extension = extension
+        self.uncompilable_modules = {}
+        self.blocked_modules = ['Cython', 'pyxbuild', 'pyximport.pyxbuild',
+                                'distutils', 'cython']
+        self.blocked_packages = ['Cython.', 'distutils.']
+
+    def find_spec(self, fullname, path, target=None):
+        if fullname in sys.modules:
+            return None
+        if any([fullname.startswith(pkg) for pkg in self.blocked_packages]):
+            return None
+        if fullname in self.blocked_modules:
+            # prevent infinite recursion
+            return None
+
+        self.blocked_modules.append(fullname)
+        name = fullname
+        if not path:
+            path = [os.getcwd()]  # top level import --
+        try:
+            for entry in path:
+                if os.path.isdir(os.path.join(entry, name)):
+                    # this module has child modules
+                    filename = os.path.join(entry, name, "__init__" + self.extension)
+                    submodule_locations = [os.path.join(entry, name)]
+                else:
+                    filename = os.path.join(entry, name + self.extension)
+                    submodule_locations = None
+                if not os.path.exists(filename):
+                    continue
+
+                return spec_from_file_location(
+                    fullname, filename,
+                    loader=PyxImportLoader(filename, self.pyxbuild_dir, self.inplace, self.language_level),
+                    submodule_search_locations=submodule_locations)
+        finally:
+            self.blocked_modules.pop()
+
+        return None  # we don't know how to import this
+
+
+class PyxImportLoader(ExtensionFileLoader):
+
+    def __init__(self, filename, pyxbuild_dir, inplace, language_level):
+        module_name = os.path.splitext(os.path.basename(filename))[0]
+        super().__init__(module_name, filename)
+        self._pyxbuild_dir = pyxbuild_dir
+        self._inplace = inplace
+        self._language_level = language_level
+
+    def create_module(self, spec):
+        try:
+            so_path = build_module(spec.name, pyxfilename=spec.origin, pyxbuild_dir=self._pyxbuild_dir,
+                                   inplace=self._inplace, language_level=self._language_level)
+            self.path = so_path
+            spec.origin = so_path
+            return super().create_module(spec)
+        except Exception as failure_exc:
+            _debug("Failed to load extension module: %r" % failure_exc)
+            if pyxargs.load_py_module_on_import_failure and spec.origin.endswith(PY_EXT):
+                spec = importlib.util.spec_from_file_location(spec.name, spec.origin,
+                                                              loader=SourceFileLoader(spec.name, spec.origin))
+                mod = importlib.util.module_from_spec(spec)
+                assert mod.__file__ in (spec.origin, spec.origin + 'c', spec.origin + 'o'), (mod.__file__, spec.origin)
+                return mod
+            else:
+                tb = sys.exc_info()[2]
+                import traceback
+                exc = ImportError("Building module %s failed: %s" % (
+                    spec.name, traceback.format_exception_only(*sys.exc_info()[:2])))
+                raise exc.with_traceback(tb)
+
+    def exec_module(self, module):
+        try:
+            return super().exec_module(module)
+        except Exception as failure_exc:
+            import traceback
+            _debug("Failed to load extension module: %r" % failure_exc)
+            raise ImportError("Executing module %s failed %s" % (
+                    module.__file__, traceback.format_exception_only(*sys.exc_info()[:2])))
+
+
+#install args
+class PyxArgs(object):
+    build_dir=True
+    build_in_temp=True
+    setup_args={}   #None
+
+
+def _have_importers():
+    has_py_importer = False
+    has_pyx_importer = False
+    for importer in sys.meta_path:
+        if isinstance(importer, PyxImportMetaFinder):
+            if isinstance(importer, PyImportMetaFinder):
+                has_py_importer = True
+            else:
+                has_pyx_importer = True
+
+    return has_py_importer, has_pyx_importer
+
+
+def install(pyximport=True, pyimport=False, build_dir=None, build_in_temp=True,
+            setup_args=None, reload_support=False,
+            load_py_module_on_import_failure=False, inplace=False,
+            language_level=None):
+    """ Main entry point for pyxinstall.
+
+    Call this to install the ``.pyx`` import hook in
+    your meta-path for a single Python process.  If you want it to be
+    installed whenever you use Python, add it to your ``sitecustomize``
+    (as described above).
+
+    :param pyximport: If set to False, does not try to import ``.pyx`` files.
+
+    :param pyimport: You can pass ``pyimport=True`` to also
+        install the ``.py`` import hook
+        in your meta-path.  Note, however, that it is rather experimental,
+        will not work at all for some ``.py`` files and packages, and will
+        heavily slow down your imports due to search and compilation.
+        Use at your own risk.
+
+    :param build_dir: By default, compiled modules will end up in a ``.pyxbld``
+        directory in the user's home directory.  Passing a different path
+        as ``build_dir`` will override this.
+
+    :param build_in_temp: If ``False``, will produce the C files locally. Working
+        with complex dependencies and debugging becomes more easy. This
+        can principally interfere with existing files of the same name.
+
+    :param setup_args: Dict of arguments for Distribution.
+        See ``distutils.core.setup()``.
+
+    :param reload_support: Enables support for dynamic
+        ``reload(my_module)``, e.g. after a change in the Cython code.
+        Additional files ``<so_path>.reloadNN`` may arise on that account, when
+        the previously loaded module file cannot be overwritten.
+
+    :param load_py_module_on_import_failure: If the compilation of a ``.py``
+        file succeeds, but the subsequent import fails for some reason,
+        retry the import with the normal ``.py`` module instead of the
+        compiled module.  Note that this may lead to unpredictable results
+        for modules that change the system state during their import, as
+        the second import will rerun these modifications in whatever state
+        the system was left after the import of the compiled module
+        failed.
+
+    :param inplace: Install the compiled module
+        (``.so`` for Linux and Mac / ``.pyd`` for Windows)
+        next to the source file.
+
+    :param language_level: The source language level to use: 2 or 3.
+        The default is to use the language level of the current Python
+        runtime for .py files and Py2 for ``.pyx`` files.
+    """
+    if setup_args is None:
+        setup_args = {}
+    if not build_dir:
+        build_dir = os.path.join(os.path.expanduser('~'), '.pyxbld')
+
+    global pyxargs
+    pyxargs = PyxArgs()  #$pycheck_no
+    pyxargs.build_dir = build_dir
+    pyxargs.build_in_temp = build_in_temp
+    pyxargs.setup_args = (setup_args or {}).copy()
+    pyxargs.reload_support = reload_support
+    pyxargs.load_py_module_on_import_failure = load_py_module_on_import_failure
+
+    has_py_importer, has_pyx_importer = _have_importers()
+    py_importer, pyx_importer = None, None
+
+    if pyimport and not has_py_importer:
+        py_importer = PyImportMetaFinder(pyxbuild_dir=build_dir, inplace=inplace,
+                                         language_level=language_level)
+        # make sure we import Cython before we install the import hook
+        import Cython.Compiler.Main, Cython.Compiler.Pipeline, Cython.Compiler.Optimize
+        sys.meta_path.insert(0, py_importer)
+
+    if pyximport and not has_pyx_importer:
+        pyx_importer = PyxImportMetaFinder(pyxbuild_dir=build_dir, inplace=inplace,
+                                           language_level=language_level)
+        sys.meta_path.append(pyx_importer)
+
+    return py_importer, pyx_importer
+
+
+def uninstall(py_importer, pyx_importer):
+    """
+    Uninstall an import hook.
+    """
+    try:
+        sys.meta_path.remove(py_importer)
+    except ValueError:
+        pass
+
+    try:
+        sys.meta_path.remove(pyx_importer)
+    except ValueError:
+        pass
+
+
+# MAIN
+
+def show_docs():
+    import __main__
+    __main__.__name__ = mod_name
+    for name in dir(__main__):
+        item = getattr(__main__, name)
+        try:
+            setattr(item, "__module__", mod_name)
+        except (AttributeError, TypeError):
+            pass
+    help(__main__)
+
+
+if __name__ == '__main__':
+    show_docs()
diff --git a/pyximport/pyximport.py b/pyximport/pyximport.py
--- a/pyximport/pyximport.py
+++ b/pyximport/pyximport.py
@@ -1,606 +1,11 @@
-"""
-Import hooks; when installed with the install() function, these hooks
-allow importing .pyx files as if they were Python modules.
-
-If you want the hook installed every time you run Python
-you can add it to your Python version by adding these lines to
-sitecustomize.py (which you can create from scratch in site-packages
-if it doesn't exist there or somewhere else on your python path)::
-
-    import pyximport
-    pyximport.install()
-
-For instance on the Mac with a non-system Python 2.3, you could create
-sitecustomize.py with only those two lines at
-/usr/local/lib/python2.3/site-packages/sitecustomize.py .
-
-A custom distutils.core.Extension instance and setup() args
-(Distribution) for for the build can be defined by a <modulename>.pyxbld
-file like:
-
-# examplemod.pyxbld
-def make_ext(modname, pyxfilename):
-    from distutils.extension import Extension
-    return Extension(name = modname,
-                     sources=[pyxfilename, 'hello.c'],
-                     include_dirs=['/myinclude'] )
-def make_setup_args():
-    return dict(script_args=["--compiler=mingw32"])
-
-Extra dependencies can be defined by a <modulename>.pyxdep .
-See README.
-
-Since Cython 0.11, the :mod:`pyximport` module also has experimental
-compilation support for normal Python modules.  This allows you to
-automatically run Cython on every .pyx and .py module that Python
-imports, including parts of the standard library and installed
-packages.  Cython will still fail to compile a lot of Python modules,
-in which case the import mechanism will fall back to loading the
-Python source modules instead.  The .py import mechanism is installed
-like this::
-
-    pyximport.install(pyimport = True)
-
-Running this module as a top-level script will run a test and then print
-the documentation.
-
-This code is based on the Py2.3+ import protocol as described in PEP 302.
-"""
-
-import glob
-import imp
-import os
+from __future__ import absolute_import
 import sys
-from zipimport import zipimporter, ZipImportError
-
-mod_name = "pyximport"
-
-PYX_EXT = ".pyx"
-PYXDEP_EXT = ".pyxdep"
-PYXBLD_EXT = ".pyxbld"
-
-DEBUG_IMPORT = False
-
-
-def _print(message, args):
-    if args:
-        message = message % args
-    print(message)
-
-
-def _debug(message, *args):
-    if DEBUG_IMPORT:
-        _print(message, args)
-
-
-def _info(message, *args):
-    _print(message, args)
-
-
-# Performance problem: for every PYX file that is imported, we will
-# invoke the whole distutils infrastructure even if the module is
-# already built. It might be more efficient to only do it when the
-# mod time of the .pyx is newer than the mod time of the .so but
-# the question is how to get distutils to tell me the name of the .so
-# before it builds it. Maybe it is easy...but maybe the performance
-# issue isn't real.
-def _load_pyrex(name, filename):
-    "Load a pyrex file given a name and filename."
-
-
-def get_distutils_extension(modname, pyxfilename, language_level=None):
-#    try:
-#        import hashlib
-#    except ImportError:
-#        import md5 as hashlib
-#    extra = "_" + hashlib.md5(open(pyxfilename).read()).hexdigest()
-#    modname = modname + extra
-    extension_mod,setup_args = handle_special_build(modname, pyxfilename)
-    if not extension_mod:
-        if not isinstance(pyxfilename, str):
-            # distutils is stupid in Py2 and requires exactly 'str'
-            # => encode accidentally coerced unicode strings back to str
-            pyxfilename = pyxfilename.encode(sys.getfilesystemencoding())
-        from distutils.extension import Extension
-        extension_mod = Extension(name = modname, sources=[pyxfilename])
-        if language_level is not None:
-            extension_mod.cython_directives = {'language_level': language_level}
-    return extension_mod,setup_args
-
-
-def handle_special_build(modname, pyxfilename):
-    special_build = os.path.splitext(pyxfilename)[0] + PYXBLD_EXT
-    ext = None
-    setup_args={}
-    if os.path.exists(special_build):
-        # globls = {}
-        # locs = {}
-        # execfile(special_build, globls, locs)
-        # ext = locs["make_ext"](modname, pyxfilename)
-        with open(special_build) as fid:
-            mod = imp.load_source("XXXX", special_build, fid)
-        make_ext = getattr(mod,'make_ext',None)
-        if make_ext:
-            ext = make_ext(modname, pyxfilename)
-            assert ext and ext.sources, "make_ext in %s did not return Extension" % special_build
-        make_setup_args = getattr(mod, 'make_setup_args',None)
-        if make_setup_args:
-            setup_args = make_setup_args()
-            assert isinstance(setup_args,dict), ("make_setup_args in %s did not return a dict"
-                                         % special_build)
-        assert set or setup_args, ("neither make_ext nor make_setup_args %s"
-                                         % special_build)
-        ext.sources = [os.path.join(os.path.dirname(special_build), source)
-                       for source in ext.sources]
-    return ext, setup_args
-
-
-def handle_dependencies(pyxfilename):
-    testing = '_test_files' in globals()
-    dependfile = os.path.splitext(pyxfilename)[0] + PYXDEP_EXT
-
-    # by default let distutils decide whether to rebuild on its own
-    # (it has a better idea of what the output file will be)
-
-    # but we know more about dependencies so force a rebuild if
-    # some of the dependencies are newer than the pyxfile.
-    if os.path.exists(dependfile):
-        with open(dependfile) as fid:
-            depends = fid.readlines()
-        depends = [depend.strip() for depend in depends]
-
-        # gather dependencies in the "files" variable
-        # the dependency file is itself a dependency
-        files = [dependfile]
-        for depend in depends:
-            fullpath = os.path.join(os.path.dirname(dependfile),
-                                    depend)
-            files.extend(glob.glob(fullpath))
-
-        # only for unit testing to see we did the right thing
-        if testing:
-            _test_files[:] = []  #$pycheck_no
-
-        # if any file that the pyxfile depends upon is newer than
-        # the pyx file, 'touch' the pyx file so that distutils will
-        # be tricked into rebuilding it.
-        for file in files:
-            from distutils.dep_util import newer
-            if newer(file, pyxfilename):
-                _debug("Rebuilding %s because of %s", pyxfilename, file)
-                filetime = os.path.getmtime(file)
-                os.utime(pyxfilename, (filetime, filetime))
-                if testing:
-                    _test_files.append(file)
-
-
-def build_module(name, pyxfilename, pyxbuild_dir=None, inplace=False, language_level=None):
-    assert os.path.exists(pyxfilename), "Path does not exist: %s" % pyxfilename
-    handle_dependencies(pyxfilename)
-
-    extension_mod, setup_args = get_distutils_extension(name, pyxfilename, language_level)
-    build_in_temp = pyxargs.build_in_temp
-    sargs = pyxargs.setup_args.copy()
-    sargs.update(setup_args)
-    build_in_temp = sargs.pop('build_in_temp',build_in_temp)
-
-    from . import pyxbuild
-    so_path = pyxbuild.pyx_to_dll(pyxfilename, extension_mod,
-                                  build_in_temp=build_in_temp,
-                                  pyxbuild_dir=pyxbuild_dir,
-                                  setup_args=sargs,
-                                  inplace=inplace,
-                                  reload_support=pyxargs.reload_support)
-    assert os.path.exists(so_path), "Cannot find: %s" % so_path
-
-    junkpath = os.path.join(os.path.dirname(so_path), name+"_*")  #very dangerous with --inplace ? yes, indeed, trying to eat my files ;)
-    junkstuff = glob.glob(junkpath)
-    for path in junkstuff:
-        if path != so_path:
-            try:
-                os.remove(path)
-            except IOError:
-                _info("Couldn't remove %s", path)
-
-    return so_path
-
-
-def load_module(name, pyxfilename, pyxbuild_dir=None, is_package=False,
-                build_inplace=False, language_level=None, so_path=None):
-    try:
-        if so_path is None:
-            if is_package:
-                module_name = name + '.__init__'
-            else:
-                module_name = name
-            so_path = build_module(module_name, pyxfilename, pyxbuild_dir,
-                                   inplace=build_inplace, language_level=language_level)
-        mod = imp.load_dynamic(name, so_path)
-        if is_package and not hasattr(mod, '__path__'):
-            mod.__path__ = [os.path.dirname(so_path)]
-        assert mod.__file__ == so_path, (mod.__file__, so_path)
-    except Exception as failure_exc:
-        _debug("Failed to load extension module: %r" % failure_exc)
-        if pyxargs.load_py_module_on_import_failure and pyxfilename.endswith('.py'):
-            # try to fall back to normal import
-            mod = imp.load_source(name, pyxfilename)
-            assert mod.__file__ in (pyxfilename, pyxfilename+'c', pyxfilename+'o'), (mod.__file__, pyxfilename)
-        else:
-            tb = sys.exc_info()[2]
-            import traceback
-            exc = ImportError("Building module %s failed: %s" % (
-                name, traceback.format_exception_only(*sys.exc_info()[:2])))
-            if sys.version_info[0] >= 3:
-                raise exc.with_traceback(tb)
-            else:
-                exec("raise exc, None, tb", {'exc': exc, 'tb': tb})
-    return mod
-
-
-# import hooks
-
-class PyxImporter(object):
-    """A meta-path importer for .pyx files.
-    """
-    def __init__(self, extension=PYX_EXT, pyxbuild_dir=None, inplace=False,
-                 language_level=None):
-        self.extension = extension
-        self.pyxbuild_dir = pyxbuild_dir
-        self.inplace = inplace
-        self.language_level = language_level
-
-    def find_module(self, fullname, package_path=None):
-        if fullname in sys.modules  and  not pyxargs.reload_support:
-            return None  # only here when reload()
-
-        # package_path might be a _NamespacePath. Convert that into a list...
-        if package_path is not None and not isinstance(package_path, list):
-            package_path = list(package_path)
-        try:
-            fp, pathname, (ext,mode,ty) = imp.find_module(fullname,package_path)
-            if fp: fp.close()  # Python should offer a Default-Loader to avoid this double find/open!
-            if pathname and ty == imp.PKG_DIRECTORY:
-                pkg_file = os.path.join(pathname, '__init__'+self.extension)
-                if os.path.isfile(pkg_file):
-                    return PyxLoader(fullname, pathname,
-                        init_path=pkg_file,
-                        pyxbuild_dir=self.pyxbuild_dir,
-                        inplace=self.inplace,
-                        language_level=self.language_level)
-            if pathname and pathname.endswith(self.extension):
-                return PyxLoader(fullname, pathname,
-                                 pyxbuild_dir=self.pyxbuild_dir,
-                                 inplace=self.inplace,
-                                 language_level=self.language_level)
-            if ty != imp.C_EXTENSION:  # only when an extension, check if we have a .pyx next!
-                return None
-
-            # find .pyx fast, when .so/.pyd exist --inplace
-            pyxpath = os.path.splitext(pathname)[0]+self.extension
-            if os.path.isfile(pyxpath):
-                return PyxLoader(fullname, pyxpath,
-                                 pyxbuild_dir=self.pyxbuild_dir,
-                                 inplace=self.inplace,
-                                 language_level=self.language_level)
-
-            # .so/.pyd's on PATH should not be remote from .pyx's
-            # think no need to implement PyxArgs.importer_search_remote here?
-
-        except ImportError:
-            pass
-
-        # searching sys.path ...
-
-        #if DEBUG_IMPORT:  print "SEARCHING", fullname, package_path
-
-        mod_parts = fullname.split('.')
-        module_name = mod_parts[-1]
-        pyx_module_name = module_name + self.extension
-
-        # this may work, but it returns the file content, not its path
-        #import pkgutil
-        #pyx_source = pkgutil.get_data(package, pyx_module_name)
-
-        paths = package_path or sys.path
-        for path in paths:
-            pyx_data = None
-            if not path:
-                path = os.getcwd()
-            elif os.path.isfile(path):
-                try:
-                    zi = zipimporter(path)
-                    pyx_data = zi.get_data(pyx_module_name)
-                except (ZipImportError, IOError, OSError):
-                    continue  # Module not found.
-                # unzip the imported file into the build dir
-                # FIXME: can interfere with later imports if build dir is in sys.path and comes before zip file
-                path = self.pyxbuild_dir
-            elif not os.path.isabs(path):
-                path = os.path.abspath(path)
-
-            pyx_module_path = os.path.join(path, pyx_module_name)
-            if pyx_data is not None:
-                if not os.path.exists(path):
-                    try:
-                        os.makedirs(path)
-                    except OSError:
-                        # concurrency issue?
-                        if not os.path.exists(path):
-                            raise
-                with open(pyx_module_path, "wb") as f:
-                    f.write(pyx_data)
-            elif not os.path.isfile(pyx_module_path):
-                continue  # Module not found.
-
-            return PyxLoader(fullname, pyx_module_path,
-                             pyxbuild_dir=self.pyxbuild_dir,
-                             inplace=self.inplace,
-                             language_level=self.language_level)
-
-        # not found, normal package, not a .pyx file, none of our business
-        _debug("%s not found" % fullname)
-        return None
-
-
-class PyImporter(PyxImporter):
-    """A meta-path importer for normal .py files.
-    """
-    def __init__(self, pyxbuild_dir=None, inplace=False, language_level=None):
-        if language_level is None:
-            language_level = sys.version_info[0]
-        self.super = super(PyImporter, self)
-        self.super.__init__(extension='.py', pyxbuild_dir=pyxbuild_dir, inplace=inplace,
-                            language_level=language_level)
-        self.uncompilable_modules = {}
-        self.blocked_modules = ['Cython', 'pyxbuild', 'pyximport.pyxbuild',
-                                'distutils']
-        self.blocked_packages = ['Cython.', 'distutils.']
-
-    def find_module(self, fullname, package_path=None):
-        if fullname in sys.modules:
-            return None
-        if any([fullname.startswith(pkg) for pkg in self.blocked_packages]):
-            return None
-        if fullname in self.blocked_modules:
-            # prevent infinite recursion
-            return None
-        if _lib_loader.knows(fullname):
-            return _lib_loader
-        _debug("trying import of module '%s'", fullname)
-        if fullname in self.uncompilable_modules:
-            path, last_modified = self.uncompilable_modules[fullname]
-            try:
-                new_last_modified = os.stat(path).st_mtime
-                if new_last_modified > last_modified:
-                    # import would fail again
-                    return None
-            except OSError:
-                # module is no longer where we found it, retry the import
-                pass
-
-        self.blocked_modules.append(fullname)
-        try:
-            importer = self.super.find_module(fullname, package_path)
-            if importer is not None:
-                if importer.init_path:
-                    path = importer.init_path
-                    real_name = fullname + '.__init__'
-                else:
-                    path = importer.path
-                    real_name = fullname
-                _debug("importer found path %s for module %s", path, real_name)
-                try:
-                    so_path = build_module(
-                        real_name, path,
-                        pyxbuild_dir=self.pyxbuild_dir,
-                        language_level=self.language_level,
-                        inplace=self.inplace)
-                    _lib_loader.add_lib(fullname, path, so_path,
-                                        is_package=bool(importer.init_path))
-                    return _lib_loader
-                except Exception:
-                    if DEBUG_IMPORT:
-                        import traceback
-                        traceback.print_exc()
-                    # build failed, not a compilable Python module
-                    try:
-                        last_modified = os.stat(path).st_mtime
-                    except OSError:
-                        last_modified = 0
-                    self.uncompilable_modules[fullname] = (path, last_modified)
-                    importer = None
-        finally:
-            self.blocked_modules.pop()
-        return importer
-
-
-class LibLoader(object):
-    def __init__(self):
-        self._libs = {}
-
-    def load_module(self, fullname):
-        try:
-            source_path, so_path, is_package = self._libs[fullname]
-        except KeyError:
-            raise ValueError("invalid module %s" % fullname)
-        _debug("Loading shared library module '%s' from %s", fullname, so_path)
-        return load_module(fullname, source_path, so_path=so_path, is_package=is_package)
-
-    def add_lib(self, fullname, path, so_path, is_package):
-        self._libs[fullname] = (path, so_path, is_package)
-
-    def knows(self, fullname):
-        return fullname in self._libs
-
-_lib_loader = LibLoader()
-
-
-class PyxLoader(object):
-    def __init__(self, fullname, path, init_path=None, pyxbuild_dir=None,
-                 inplace=False, language_level=None):
-        _debug("PyxLoader created for loading %s from %s (init path: %s)",
-               fullname, path, init_path)
-        self.fullname = fullname
-        self.path, self.init_path = path, init_path
-        self.pyxbuild_dir = pyxbuild_dir
-        self.inplace = inplace
-        self.language_level = language_level
-
-    def load_module(self, fullname):
-        assert self.fullname == fullname, (
-            "invalid module, expected %s, got %s" % (
-            self.fullname, fullname))
-        if self.init_path:
-            # package
-            #print "PACKAGE", fullname
-            module = load_module(fullname, self.init_path,
-                                 self.pyxbuild_dir, is_package=True,
-                                 build_inplace=self.inplace,
-                                 language_level=self.language_level)
-            module.__path__ = [self.path]
-        else:
-            #print "MODULE", fullname
-            module = load_module(fullname, self.path,
-                                 self.pyxbuild_dir,
-                                 build_inplace=self.inplace,
-                                 language_level=self.language_level)
-        return module
-
-
-#install args
-class PyxArgs(object):
-    build_dir=True
-    build_in_temp=True
-    setup_args={}   #None
-
-##pyxargs=None
-
-
-def _have_importers():
-    has_py_importer = False
-    has_pyx_importer = False
-    for importer in sys.meta_path:
-        if isinstance(importer, PyxImporter):
-            if isinstance(importer, PyImporter):
-                has_py_importer = True
-            else:
-                has_pyx_importer = True
-
-    return has_py_importer, has_pyx_importer
-
-
-def install(pyximport=True, pyimport=False, build_dir=None, build_in_temp=True,
-            setup_args=None, reload_support=False,
-            load_py_module_on_import_failure=False, inplace=False,
-            language_level=None):
-    """ Main entry point for pyxinstall.
-
-    Call this to install the ``.pyx`` import hook in
-    your meta-path for a single Python process.  If you want it to be
-    installed whenever you use Python, add it to your ``sitecustomize``
-    (as described above).
-
-    :param pyximport: If set to False, does not try to import ``.pyx`` files.
-
-    :param pyimport: You can pass ``pyimport=True`` to also
-        install the ``.py`` import hook
-        in your meta-path.  Note, however, that it is rather experimental,
-        will not work at all for some ``.py`` files and packages, and will
-        heavily slow down your imports due to search and compilation.
-        Use at your own risk.
-
-    :param build_dir: By default, compiled modules will end up in a ``.pyxbld``
-        directory in the user's home directory.  Passing a different path
-        as ``build_dir`` will override this.
-
-    :param build_in_temp: If ``False``, will produce the C files locally. Working
-        with complex dependencies and debugging becomes more easy. This
-        can principally interfere with existing files of the same name.
-
-    :param setup_args: Dict of arguments for Distribution.
-        See ``distutils.core.setup()``.
-
-    :param reload_support: Enables support for dynamic
-        ``reload(my_module)``, e.g. after a change in the Cython code.
-        Additional files ``<so_path>.reloadNN`` may arise on that account, when
-        the previously loaded module file cannot be overwritten.
-
-    :param load_py_module_on_import_failure: If the compilation of a ``.py``
-        file succeeds, but the subsequent import fails for some reason,
-        retry the import with the normal ``.py`` module instead of the
-        compiled module.  Note that this may lead to unpredictable results
-        for modules that change the system state during their import, as
-        the second import will rerun these modifications in whatever state
-        the system was left after the import of the compiled module
-        failed.
-
-    :param inplace: Install the compiled module
-        (``.so`` for Linux and Mac / ``.pyd`` for Windows)
-        next to the source file.
-
-    :param language_level: The source language level to use: 2 or 3.
-        The default is to use the language level of the current Python
-        runtime for .py files and Py2 for ``.pyx`` files.
-    """
-    if setup_args is None:
-        setup_args = {}
-    if not build_dir:
-        build_dir = os.path.join(os.path.expanduser('~'), '.pyxbld')
-
-    global pyxargs
-    pyxargs = PyxArgs()  #$pycheck_no
-    pyxargs.build_dir = build_dir
-    pyxargs.build_in_temp = build_in_temp
-    pyxargs.setup_args = (setup_args or {}).copy()
-    pyxargs.reload_support = reload_support
-    pyxargs.load_py_module_on_import_failure = load_py_module_on_import_failure
-
-    has_py_importer, has_pyx_importer = _have_importers()
-    py_importer, pyx_importer = None, None
-
-    if pyimport and not has_py_importer:
-        py_importer = PyImporter(pyxbuild_dir=build_dir, inplace=inplace,
-                                 language_level=language_level)
-        # make sure we import Cython before we install the import hook
-        import Cython.Compiler.Main, Cython.Compiler.Pipeline, Cython.Compiler.Optimize
-        sys.meta_path.insert(0, py_importer)
-
-    if pyximport and not has_pyx_importer:
-        pyx_importer = PyxImporter(pyxbuild_dir=build_dir, inplace=inplace,
-                                   language_level=language_level)
-        sys.meta_path.append(pyx_importer)
-
-    return py_importer, pyx_importer
-
-
-def uninstall(py_importer, pyx_importer):
-    """
-    Uninstall an import hook.
-    """
-    try:
-        sys.meta_path.remove(py_importer)
-    except ValueError:
-        pass
-
-    try:
-        sys.meta_path.remove(pyx_importer)
-    except ValueError:
-        pass
-
-
-# MAIN
-
-def show_docs():
-    import __main__
-    __main__.__name__ = mod_name
-    for name in dir(__main__):
-        item = getattr(__main__, name)
-        try:
-            setattr(item, "__module__", mod_name)
-        except (AttributeError, TypeError):
-            pass
-    help(__main__)
 
+if sys.version_info < (3, 5):
+    # _pyximport3 module requires at least Python 3.5
+    from pyximport._pyximport2 import install, uninstall, show_docs
+else:
+    from pyximport._pyximport3 import install, uninstall, show_docs
 
 if __name__ == '__main__':
     show_docs()


Test patch: