Mac/IDLE/idlemain.py

   1 """
   2 Bootstrap script for IDLE as an application bundle.
   3 """
   4 import sys, os
   5
   6 # Change the current directory the user's home directory, that way we'll get
   7 # a more useful default location in the open/save dialogs.
   8 os.chdir(os.path.expanduser('~/Documents'))
   9
  10
  11 # Make sure sys.executable points to the python interpreter inside the
  12 # framework, instead of at the helper executable inside the application
  13 # bundle (the latter works, but doesn't allow access to the window server)
  14 #
  15 #  .../IDLE.app/
  16 #       Contents/
  17 #           MacOS/
  18 #               IDLE (a python script)
  19 #               Python{-32} (symlink)
  20 #           Resources/
  21 #               idlemain.py (this module)
  22 #               ...
  23 #
  24 # ../IDLE.app/Contents/MacOS/Python{-32} is symlinked to
  25 #       ..Library/Frameworks/Python.framework/Versions/m.n
  26 #                   /Resources/Python.app/Contents/MacOS/Python{-32}
  27 #       which is the Python interpreter executable
  28 #
  29 # The flow of control is as follows:
  30 # 1. IDLE.app is launched which starts python running the IDLE script
  31 # 2. IDLE script exports
  32 #       PYTHONEXECUTABLE = .../IDLE.app/Contents/MacOS/Python{-32}
  33 #           (the symlink to the framework python)
  34 # 3. IDLE script alters sys.argv and uses os.execve to replace itself with
  35 #       idlemain.py running under the symlinked python.
  36 #       This is the magic step.
  37 # 4. During interpreter initialization, because PYTHONEXECUTABLE is defined,
  38 #    sys.executable may get set to an unuseful value.
  39 #
  40 # (Note that the IDLE script and the setting of PYTHONEXECUTABLE is
  41 #  generated automatically by bundlebuilder in the Python 2.x build.
  42 #  Also, IDLE invoked via command line, i.e. bin/idle, bypasses all of
  43 #  this.)
  44 #
  45 # Now fix up the execution environment before importing idlelib.
  46
  47 # Reset sys.executable to its normal value, the actual path of
  48 # the interpreter in the framework, by following the symlink
  49 # exported in PYTHONEXECUTABLE.
  50 pyex = os.environ['PYTHONEXECUTABLE']
  51 sys.executable = os.path.join(os.path.dirname(pyex), os.readlink(pyex))
  52
  53 # Remove any sys.path entries for the Resources dir in the IDLE.app bundle.
  54 p = pyex.partition('.app')
  55 if p[2].startswith('/Contents/MacOS/Python'):
  56     sys.path = [value for value in sys.path if
  57             value.partition('.app') != (p[0], p[1], '/Contents/Resources')]
  58
  59 # Unexport PYTHONEXECUTABLE so that the other Python processes started
  60 # by IDLE have a normal sys.executable.
  61 del os.environ['PYTHONEXECUTABLE']
  62
  63 # Look for the -psn argument that the launcher adds and remove it, it will
  64 # only confuse the IDLE startup code.
  65 for idx, value in enumerate(sys.argv):
  66     if value.startswith('-psn_'):
  67         del sys.argv[idx]
  68         break
  69
  70 # Now it is safe to import idlelib.
  71 from idlelib.PyShell import main
  72 if __name__ == '__main__':
  73     main()