pass back python bin from configure

pylib/gyp/__init__.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 Google Inc. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import copy
 import gyp.input
 import optparse
 import os.path
@@ skipping 52 matching lines @@
   if '-' in format:
     format, params['flavor'] = format.split('-', 1)
 
   default_variables = copy.copy(default_variables)
 
   # Default variables provided by this program and its modules should be
   # named WITH_CAPITAL_LETTERS to provide a distinct "best practice" namespace,
   # avoiding collisions with user and automatic variables.
   default_variables['GENERATOR'] = format
 
+  # Provide a PYTHON value to run sub-commands with the same python
+  default_variables['PYTHON'] = sys.executable

[Mark Mentovai, 2013/03/04 21:24:53]

default_variables isn’t right. Which commands are you interested in having
PYTHON set for? Various ones that might run from within GYP? You’ll want to set
PYTHON in the environment. Commands that might be invoked during a build
(post-GYP)? There’s no guarantee that anything in default_variables gets
exported to the environment.

I don’t think this function is the right spot for this, either. If you’re going
to alter the environment, you probably want to use gyp_main, not Load.

[Evan Martin, 2013/03/05 17:05:49]

(I glanced at the Mozilla patch that prompted this)

They are writing their action commands lines like (sorry for forgetting gyp
syntax):
"<(PYTHON) foo.py <(INPUTS)"
which is why the above works for them.

[tony, 2013/03/05 22:33:24]

Is it possible to use <!@pymod_do_main(foo <@(INPUTS)) to execute code from
foo.py without spawning a new python process? See
https://code.google.com/p/gyp/source/detail?r=924

+
   # Format can be a custom python file, or by default the name of a module
   # within gyp.generator.
   if format.endswith('.py'):
     generator_name = os.path.splitext(format)[0]
     path, generator_name = os.path.split(generator_name)
 
     # Make sure the path to the custom generator is in sys.path
     # Don't worry about removing it once we are done.  Keeping the path
     # to each generator that is used in sys.path is likely harmless and
     # arguably a good idea.
@@ skipping 440 matching lines @@
 
 def main(args):
   try:
     return gyp_main(args)
   except GypError, e:
     sys.stderr.write("gyp: %s\n" % e)
     return 1
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))