req_install.py 文件源码

def from_editable(cls, editable_req, comes_from=None, isolated=False,
                      options=None, wheel_cache=None, constraint=False):
        from pip._internal.index import Link

        name, url, extras_override = parse_editable(editable_req)
        if url.startswith('file:'):
            source_dir = url_to_path(url)
        else:
            source_dir = None

        if name is not None:
            try:
                req = Requirement(name)
            except InvalidRequirement:
                raise InstallationError("Invalid requirement: '%s'" % req)
        else:
            req = None
        return cls(
            req, comes_from, source_dir=source_dir,
            editable=True,
            link=Link(url),
            constraint=constraint,
            isolated=isolated,
            options=options if options else {},
            wheel_cache=wheel_cache,
            extras=extras_override or (),
        )