1 # Protocol Buffers - Google's data interchange format 2 # Copyright 2008 Google Inc. All rights reserved. 3 # http://code.google.com/p/protobuf/ 4 # 5 # Redistribution and use in source and binary forms, with or without 6 # modification, are permitted provided that the following conditions are 7 # met: 8 # 9 # * Redistributions of source code must retain the above copyright 10 # notice, this list of conditions and the following disclaimer. 11 # * Redistributions in binary form must reproduce the above 12 # copyright notice, this list of conditions and the following disclaimer 13 # in the documentation and/or other materials provided with the 14 # distribution. 15 # * Neither the name of Google Inc. nor the names of its 16 # contributors may be used to endorse or promote products derived from 17 # this software without specific prior written permission. 18 # 19 # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20 # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21 # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22 # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23 # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24 # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25 # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26 # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27 # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28 # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31 """ 32 This module is the central entity that determines which implementation of the 33 API is used. 34 """ 35 36 __author__ = 'petar (at] google.com (Petar Petrov)' 37 38 import os 39 # This environment variable can be used to switch to a certain implementation 40 # of the Python API. Right now only 'python' and 'cpp' are valid values. Any 41 # other value will be ignored. 42 _implementation_type = os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION', 43 'python') 44 45 46 if _implementation_type != 'python': 47 # For now, by default use the pure-Python implementation. 48 # The code below checks if the C extension is available and 49 # uses it if it is available. 50 _implementation_type = 'cpp' 51 ## Determine automatically which implementation to use. 52 #try: 53 # from google.protobuf.internal import cpp_message 54 # _implementation_type = 'cpp' 55 #except ImportError, e: 56 # _implementation_type = 'python' 57 58 59 # This environment variable can be used to switch between the two 60 # 'cpp' implementations. Right now only 1 and 2 are valid values. Any 61 # other value will be ignored. 62 _implementation_version_str = os.getenv( 63 'PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION', 64 '1') 65 66 67 if _implementation_version_str not in ('1', '2'): 68 raise ValueError( 69 "unsupported PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION_VERSION: '" + 70 _implementation_version_str + "' (supported versions: 1, 2)" 71 ) 72 73 74 _implementation_version = int(_implementation_version_str) 75 76 77 78 # Usage of this function is discouraged. Clients shouldn't care which 79 # implementation of the API is in use. Note that there is no guarantee 80 # that differences between APIs will be maintained. 81 # Please don't use this function if possible. 82 def Type(): 83 return _implementation_type 84 85 # See comment on 'Type' above. 86 def Version(): 87 return _implementation_version 88
