json_util.py 文件源码

def __new__(mcs, name, bases, dikt):
        fields = {}

        for base in bases:
            fields.update(getattr(base, '_fields', {}))
        # Do not reorder, this class might override fields from base classes!
        for key, value in tuple(six.iteritems(dikt)):
            # not six.iterkeys() (in-place edit!)
            if isinstance(value, Field):
                fields[key] = dikt.pop(key)

        dikt['_orig_slots'] = dikt.get('__slots__', ())
        dikt['__slots__'] = tuple(
            list(dikt['_orig_slots']) + list(six.iterkeys(fields)))
        dikt['_fields'] = fields

        return abc.ABCMeta.__new__(mcs, name, bases, dikt)