Dynamically generate a setuptools / pkg_resources entry point

entrypoint.py

class FakeModuleFinderLoader(object):
    def find_module(self, fullname, path=None):
        if fullname == "fake_module":
            return self

    def load_module(self, fullname):
        mod = sys.modules.setdefault(fullname, imp.new_module(fullname))
        mod.__file__ = "<fake_module>"
        mod.__loader__ = self
        mod.__package__ = fullname.rpartition('.')[0]

        # Add attributes here
        mod.__dict__['keyword_handler'] = lambda: dist, attr, value: print(dist, attr, value)

        return mod


def fake_module_path_hook(path):
    if path == "_FAKE_":
        return FakeModuleFinderLoader()


class FakeMetadata(pkg_resources.EmptyProvider):
    def has_metadata(self, name):
        return name in ('PKG-INFO', 'entry_points.txt')

    def get_metadata(self, name):
        print("get_metadata", name)
        if name == 'PKG-INFO':
            return textwrap.dedent("""\
                Metadata-Version: 1.1
                Name: fake-package
                Version: 1.0.0
            """)
        elif name == 'entry_points.txt':
            return textwrap.dedent("""\
                [distutils.setup_keywords]
                keyword = fake_module:keyword_handler
            """)

        raise KeyError("No metadata except PKG-INFO and entry_points.txt is available")

    def get_metadata_lines(self, name):
        return pkg_resources.yield_lines(self.get_metadata(name))


def fake_adapter(importer, path_item, only=False):
    yield pkg_resources.Distribution(path_item, metadata=FakeMetadata())

pkg_resources.register_finder(FakeModuleFinderLoader, fake_adapter)
sys.path_hooks.append(fake_module_path_hook)
pkg_resources.working_set.add_entry('_FAKE_')