requirements.py 文件源码

def __init__(self, requirement_string):
        try:
            req = REQUIREMENT.parseString(requirement_string)
        except ParseException as e:
            raise InvalidRequirement(
                "Invalid requirement, parse error at \"{0!r}\"".format(
                    requirement_string[e.loc:e.loc + 8]))

        self.name = req.name
        if req.url:
            parsed_url = urlparse.urlparse(req.url)
            if not (parsed_url.scheme and parsed_url.netloc) or (
                    not parsed_url.scheme and not parsed_url.netloc):
                raise InvalidRequirement("Invalid URL given")
            self.url = req.url
        else:
            self.url = None
        self.extras = set(req.extras.asList() if req.extras else [])
        self.specifier = SpecifierSet(req.specifier)
        self.marker = req.marker if req.marker else None