_dummy_os.py

"""
A shim of the os module containing only simple path-related utilities
"""

try:
    from os import *
except ImportError:
    import abc

    def __getattr__(name):
        raise OSError("no os specific module found")

    def _shim():
        import _dummy_os, sys
        sys.modules['os'] = _dummy_os
        sys.modules['os.path'] = _dummy_os.path

    import posixpath as path
    import sys
    sys.modules['os.path'] = path
    del sys

    sep = path.sep


    def fspath(path):
        """Return the path representation of a path-like object.

        If str or bytes is passed in, it is returned unchanged. Otherwise the
        os.PathLike interface is used to get the path representation. If the
        path representation is not str or bytes, TypeError is raised. If the
        provided path is not str, bytes, or os.PathLike, TypeError is raised.
        """
        if isinstance(path, (str, bytes)):
            return path

        # Work from the object's type to match method resolution of other magic
        # methods.
        path_type = type(path)
        try:
            path_repr = path_type.__fspath__(path)
        except AttributeError:
            if hasattr(path_type, '__fspath__'):
                raise
            else:
                raise TypeError("expected str, bytes or os.PathLike object, "
                                "not " + path_type.__name__)
        if isinstance(path_repr, (str, bytes)):
            return path_repr
        else:
            raise TypeError("expected {}.__fspath__() to return str or bytes, "
                            "not {}".format(path_type.__name__,
                                            type(path_repr).__name__))

    class PathLike(abc.ABC):

        """Abstract base class for implementing the file system path protocol."""

        @abc.abstractmethod
        def __fspath__(self):
            """Return the file system path representation of the object."""
            raise NotImplementedError

        @classmethod
        def __subclasshook__(cls, subclass):
            return hasattr(subclass, '__fspath__')