def load(self, requirements_file=None):
        """Load or reload requirements from a requirements.txt file.

        :param requirements_file: if not given, the filename used from
            initialization will be read again.
        """
        if requirements_file is None:
            requirements_file = self.filename
            if requirements_file is None:
                raise ValueError("no filename provided")
        elif isinstance(requirements_file, text_type):
            requirements_file = Path(requirements_file)
        self.clear()
        with requirements_file.open() as f:
            self.loads(f.read())

        if isinstance(requirements_file, (text_type, Path)):
            self.filename = requirements_file
def __init__(self, path, matcher):
        super(subdirmatcher, self).__init__(matcher._root, matcher._cwd)
        self._path = path
        self._matcher = matcher
        self._always = matcher.always()

        self._files = [
            f[len(path) + 1 :] for f in matcher._files if f.startswith(path + "/")
        ]

        # If the parent repo had a path to this subrepo and the matcher is
        # a prefix matcher, this submatcher always matches.
        if matcher.prefix():
            self._always = any(f == path for f in matcher._files)