util.py 文件源码

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:
            six.raise_from(ValueError('{}.__spec__ is not set'.format(name)), None)
        else:
            if spec is None:
                raise ValueError('{}.__spec__ is None'.format(name))
            return spec