Source Code for Package SCons.compat

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 23   
 24  __doc__ = """ 
 25  SCons compatibility package for old Python versions 
 26   
 27  This subpackage holds modules that provide backwards-compatible 
 28  implementations of various things that we'd like to use in SCons but which 
 29  only show up in later versions of Python than the early, old version(s) 
 30  we still support. 
 31   
 32  Other code will not generally reference things in this package through 
 33  the SCons.compat namespace.  The modules included here add things to 
 34  the builtins namespace or the global module list so that the rest 
 35  of our code can use the objects and names imported here regardless of 
 36  Python version. 
 37   
 38  Simply enough, things that go in the builtins name space come from 
 39  our _scons_builtins module. 
 40   
 41  The rest of the things here will be in individual compatibility modules 
 42  that are either: 1) suitably modified copies of the future modules that 
 43  we want to use; or 2) backwards compatible re-implementations of the 
 44  specific portions of a future module's API that we want to use. 
 45   
 46  GENERAL WARNINGS:  Implementations of functions in the SCons.compat 
 47  modules are *NOT* guaranteed to be fully compliant with these functions in 
 48  later versions of Python.  We are only concerned with adding functionality 
 49  that we actually use in SCons, so be wary if you lift this code for 
 50  other uses.  (That said, making these more nearly the same as later, 
 51  official versions is still a desirable goal, we just don't need to be 
 52  obsessive about it.) 
 53   
 54  We name the compatibility modules with an initial '_scons_' (for example, 
 55  _scons_subprocess.py is our compatibility module for subprocess) so 
 56  that we can still try to import the real module name and fall back to 
 57  our compatibility module if we get an ImportError.  The import_as() 
 58  function defined below loads the module as the "real" name (without the 
 59  '_scons'), after which all of the "import {module}" statements in the 
 60  rest of our code will find our pre-loaded compatibility module. 
 61  """ 
 62   
 63  __revision__ = "src/engine/SCons/compat/__init__.py 5023 2010/06/14 22:05:46 scons" 
 64   
 65  import os 
 66  import sys 
 67  import imp   # Use the "imp" module to protect imports from fixers. 
 68   
 69 -def import_as(module, name): 
 70      """ 
 71      Imports the specified module (from our local directory) as the 
 72      specified name, returning the loaded module object. 
 73      """ 
 74      dir = os.path.split(__file__)[0] 
 75      return imp.load_module(name, *imp.find_module(module, [dir])) 
 76   
 77 -def rename_module(new, old): 
 78      """ 
 79      Attempts to import the old module and load it under the new name. 
 80      Used for purely cosmetic name changes in Python 3.x. 
 81      """ 
 82      try: 
 83          sys.modules[new] = imp.load_module(old, *imp.find_module(old)) 
 84          return True 
 85      except ImportError: 
 86          return False 
 87   
 88   
 89  rename_module('builtins', '__builtin__') 
 90  import _scons_builtins 
 91   
 92   
 93  try: 
 94      import hashlib 
 95  except ImportError: 
 96      # Pre-2.5 Python has no hashlib module. 
 97      try: 
 98          import_as('_scons_hashlib', 'hashlib') 
 99      except ImportError: 
100          # If we failed importing our compatibility module, it probably 
101          # means this version of Python has no md5 module.  Don't do 
102          # anything and let the higher layer discover this fact, so it 
103          # can fall back to using timestamp. 
104          pass 
105   
106  try: 
107      set 
108  except NameError: 
109      # Pre-2.4 Python has no native set type 
110      import_as('_scons_sets', 'sets') 
111      import builtins, sets 
112      builtins.set = sets.Set 
113   
114   
115  try: 
116      import collections 
117  except ImportError: 
118      # Pre-2.4 Python has no collections module. 
119      import_as('_scons_collections', 'collections') 
120  else: 
121      try: 
122          collections.UserDict 
123      except AttributeError: 
124          exec('from UserDict import UserDict as _UserDict') 
125          collections.UserDict = _UserDict 
126          del _UserDict 
127      try: 
128          collections.UserList 
129      except AttributeError: 
130          exec('from UserList import UserList as _UserList') 
131          collections.UserList = _UserList 
132          del _UserList 
133      try: 
134          collections.UserString 
135      except AttributeError: 
136          exec('from UserString import UserString as _UserString') 
137          collections.UserString = _UserString 
138          del _UserString 
139   
140   
141  try: 
142      import io 
143  except ImportError: 
144      # Pre-2.6 Python has no io module. 
145      import_as('_scons_io', 'io') 
146   
147   
148  try: 
149      os.devnull 
150  except AttributeError: 
151      # Pre-2.4 Python has no os.devnull attribute 
152      _names = sys.builtin_module_names 
153      if 'posix' in _names: 
154          os.devnull = '/dev/null' 
155      elif 'nt' in _names: 
156          os.devnull = 'nul' 
157      os.path.devnull = os.devnull 
158  try: 
159      os.path.lexists 
160  except AttributeError: 
161      # Pre-2.4 Python has no os.path.lexists function 
162 -    def lexists(path): 
163          return os.path.exists(path) or os.path.islink(path) 
164      os.path.lexists = lexists 
165   
166   
167  # When we're using the '-3' option during regression tests, importing 
168  # cPickle gives a warning no matter how it's done, so always use the 
169  # real profile module, whether it's fast or not. 
170  if os.environ.get('SCONS_HORRIBLE_REGRESSION_TEST_HACK') is None: 
171      # Not a regression test with '-3', so try to use faster version. 
172      # In 3.x, 'pickle' automatically loads the fast version if available. 
173      rename_module('pickle', 'cPickle') 
174   
175   
176  # In 3.x, 'profile' automatically loads the fast version if available. 
177  rename_module('profile', 'cProfile') 
178   
179   
180  # Before Python 3.0, the 'queue' module was named 'Queue'. 
181  rename_module('queue', 'Queue') 
182   
183   
184  # Before Python 3.0, the 'winreg' module was named '_winreg' 
185  rename_module('winreg', '_winreg') 
186   
187   
188  try: 
189      import subprocess 
190  except ImportError: 
191      # Pre-2.4 Python has no subprocess module. 
192      import_as('_scons_subprocess', 'subprocess') 
193   
194  try: 
195      sys.intern 
196  except AttributeError: 
197      # Pre-2.6 Python has no sys.intern() function. 
198      import builtins 
199      try: 
200          sys.intern = builtins.intern 
201      except AttributeError: 
202          # Pre-2.x Python has no builtin intern() function. 
203 -        def intern(x): 
204             return x 
205          sys.intern = intern 
206          del intern 
207  try: 
208      sys.maxsize 
209  except AttributeError: 
210      # Pre-2.6 Python has no sys.maxsize attribute 
211      # Wrapping sys in () is silly, but protects it from 2to3 renames fixer 
212      sys.maxsize = (sys).maxint 
213   
214   
215  if os.environ.get('SCONS_HORRIBLE_REGRESSION_TEST_HACK') is not None: 
216      # We can't apply the 'callable' fixer until the floor is 2.6, but the 
217      # '-3' option to Python 2.6 and 2.7 generates almost ten thousand 
218      # warnings.  This hack allows us to run regression tests with the '-3' 
219      # option by replacing the callable() built-in function with a hack 
220      # that performs the same function but doesn't generate the warning. 
221      # Note that this hack is ONLY intended to be used for regression 
222      # testing, and should NEVER be used for real runs. 
223      from types import ClassType 
224 -    def callable(obj): 
225          if hasattr(obj, '__call__'): return True 
226          if isinstance(obj, (ClassType, type)): return True 
227          return False 
228      import builtins 
229      builtins.callable = callable 
230      del callable 
231   
232   
233  # Local Variables: 
234  # tab-width:4 
235  # indent-tabs-mode:nil 
236  # End: 
237  # vim: set expandtab tabstop=4 shiftwidth=4: 
238