1# Protocol Buffers - Google's data interchange format
2# Copyright 2008 Google Inc. All rights reserved.
3#
4# Use of this source code is governed by a BSD-style
5# license that can be found in the LICENSE file or at
6# https://developers.google.com/open-source/licenses/bsd
7
8# This code is meant to work on Python 2.4 and above only.
9
10"""Contains a metaclass and helper functions used to create
11protocol message classes from Descriptor objects at runtime.
12
13Recall that a metaclass is the "type" of a class.
14(A class is to a metaclass what an instance is to a class.)
15
16In this case, we use the GeneratedProtocolMessageType metaclass
17to inject all the useful functionality into the classes
18output by the protocol compiler at compile-time.
19
20The upshot of all this is that the real implementation
21details for ALL pure-Python protocol buffers are *here in
22this file*.
23"""
24
25__author__ = 'robinson@google.com (Will Robinson)'
26
27import warnings
28
29from google.protobuf import message_factory
30from google.protobuf import symbol_database
31
32# The type of all Message classes.
33# Part of the public interface, but normally only used by message factories.
34GeneratedProtocolMessageType = message_factory._GENERATED_PROTOCOL_MESSAGE_TYPE
35
36MESSAGE_CLASS_CACHE = {}