cache.py 文件源码

def _get_cached_requirements(self):
        import os.path
        import pkg_resources

        path = os.path.join(self._cache_dir, 'requirements.txt')

        if not os.path.exists(path):
            # No cached requirements. The empty set will always trigger a cache
            # refresh because the current requirements will, at minimum,
            # contain q2cli.
            return set()
        else:
            with open(path, 'r') as fh:
                contents = fh.read()
            try:
                return set(pkg_resources.parse_requirements(contents))
            except pkg_resources.RequirementParseError:
                # Unreadable cached requirements, trigger a cache refresh.
                return set()