imputil.py 文件源码

def _import_one(self, parent, modname, fqname):
        "Import a single module."

        # has the module already been imported?
        try:
            return sys.modules[fqname]
        except KeyError:
            pass

        # load the module's code, or fetch the module itself
        result = self.get_code(parent, modname, fqname)
        if result is None:
            return None

        module = self._process_result(result, fqname)

        # insert the module into its parent
        if parent:
            setattr(parent, modname, module)
        return module