text: #!/usr/bin/env python
  """Multithreaded interactive interpreter with GTK and Matplotlib support.
  
  Usage:
  
    pyint-gtk.py -> starts shell with gtk thread running separately
  
    pyint-gtk.py -pylab [filename] -> initializes matplotlib, optionally running
    the named file.  The shell starts after the file is executed.
  
  Threading code taken from:
  http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/65109, by Brian
  McErlean and John Finlay.
  
  Matplotlib support taken from interactive.py in the matplotlib distribution.
  
  Also borrows liberally from code.py in the Python standard library."""
  
  __author__ = "Fernando Perez <Fernando.Perez@colorado.edu>"
  
  import sys
  import code
  import threading
  
  import gobject
  import gtk
  
  try:
      import readline
  except ImportError:
      has_readline = False
  else:
      has_readline = True
  
  class MTConsole(code.InteractiveConsole):
      """Simple multi-threaded shell"""
  
      def __init__(self,on_kill=None,*args,**kw):
          code.InteractiveConsole.__init__(self,*args,**kw)
          self.code_to_run = None
          self.ready = threading.Condition()
          self._kill = False
          if on_kill is None:
              on_kill = []
          # Check that all things to kill are callable:
          for _ in on_kill:
              if not callable(_):
                  raise TypeError,'on_kill must be a list of callables'
          self.on_kill = on_kill
          # Set up tab-completer
          if has_readline:
              import rlcompleter
              try:  # this form only works with python 2.3
                  self.completer = rlcompleter.Completer(self.locals)
              except: # simpler for py2.2
                  self.completer = rlcompleter.Completer()
  
              readline.set_completer(self.completer.complete)
              # Use tab for completions
              readline.parse_and_bind('tab: complete')
              # This forces readline to automatically print the above list when tab
              # completion is set to 'complete'.
              readline.parse_and_bind('set show-all-if-ambiguous on')
              # Bindings for incremental searches in the history. These searches
              # use the string typed so far on the command line and search
              # anything in the previous input history containing them.
              readline.parse_and_bind('"\C-r": reverse-search-history')
              readline.parse_and_bind('"\C-s": forward-search-history')
  
      def runsource(self, source, filename="<input>", symbol="single"):
          """Compile and run some source in the interpreter.
  
          Arguments are as for compile_command().
  
          One several things can happen:
  
          1) The input is incorrect; compile_command() raised an
          exception (SyntaxError or OverflowError).  A syntax traceback
          will be printed by calling the showsyntaxerror() method.
  
          2) The input is incomplete, and more input is required;
          compile_command() returned None.  Nothing happens.
  
          3) The input is complete; compile_command() returned a code
          object.  The code is executed by calling self.runcode() (which
          also handles run-time exceptions, except for SystemExit).
  
          The return value is True in case 2, False in the other cases (unless
          an exception is raised).  The return value can be used to
          decide whether to use sys.ps1 or sys.ps2 to prompt the next
          line.
          """
          try:
              code = self.compile(source, filename, symbol)
          except (OverflowError, SyntaxError, ValueError):
              # Case 1
              self.showsyntaxerror(filename)
              return False
  
          if code is None:
              # Case 2
              return True
  
          # Case 3
          # Store code in self, so the execution thread can handle it
          self.ready.acquire()
          self.code_to_run = code
          self.ready.wait()  # Wait until processed in timeout interval
          self.ready.release()
  
          return False
  
      def runcode(self):
          """Execute a code object.
  
          When an exception occurs, self.showtraceback() is called to display a
          traceback."""
  
          self.ready.acquire()
          if self._kill:
              print 'Closing threads...',
              sys.stdout.flush()
              for tokill in self.on_kill:
                  tokill()
              print 'Done.'
  
          if self.code_to_run is not None:
              self.ready.notify()
              code.InteractiveConsole.runcode(self,self.code_to_run)
  
          self.code_to_run = None
          self.ready.release()
          return True
  
      def kill (self):
          """Kill the thread, returning when it has been shut down."""
          self.ready.acquire()
          self._kill = True
          self.ready.release()
  
  class GTKInterpreter(threading.Thread):
      """Run gtk.main in the main thread and a python interpreter in a
      separate thread.
      Python commands can be passed to the thread where they will be executed.
      This is implemented by periodically checking for passed code using a
      GTK timeout callback.
      """
      TIMEOUT = 100 # Millisecond interval between timeouts.
  
      def __init__(self,banner=None):
          threading.Thread.__init__(self)
          self.banner = banner
          self.shell = MTConsole(on_kill=[gtk.main_quit])
  
      def run(self):
          self.pre_interact()
          self.shell.interact(self.banner)
          self.shell.kill()
  
      def mainloop(self):
          self.start()
          gobject.timeout_add(self.TIMEOUT, self.shell.runcode)
          try:
              if gtk.gtk_version[0] >= 2:
                  gtk.gdk.threads_init()
          except AttributeError:
              pass
          gtk.main()
          self.join()
  
      def pre_interact(self):
          """This method should be overridden by subclasses.
  
          It gets called right before interact(), but after the thread starts.
          Typically used to push initialization code into the interpreter"""
  
          pass
  
  class MatplotLibInterpreter(GTKInterpreter):
      """Threaded interpreter with matplotlib support.
  
      Note that this explicitly sets GTKAgg as the backend, since it has
      specific GTK hooks in it."""
  
      def __init__(self,banner=None):
          banner = """\nWelcome to matplotlib, a matlab-like python environment.
      help(matlab)   -> help on matlab compatible commands from matplotlib.
      help(plotting) -> help on plotting commands.
      """
          GTKInterpreter.__init__(self,banner)
  
      def pre_interact(self):
          """Initialize matplotlib before user interaction begins"""
  
          push = self.shell.push
          # Code to execute in user's namespace
          lines = ["import matplotlib",
                   "matplotlib.use('GTKAgg')",
                   "matplotlib.interactive(1)",
                   "import matplotlib.pylab as pylab",
                   "from matplotlib.pylab import *\n"]
  
          map(push,lines)
  
          # Execute file if given.
          if len(sys.argv)>1:
              import matplotlib
              matplotlib.interactive(0) # turn off interaction
              fname = sys.argv[1]
              try:
                  inFile = file(fname, 'r')
              except IOError:
                  print '*** ERROR *** Could not read file <%s>' % fname
              else:
                  print '*** Executing file <%s>:' % fname
                  for line in inFile:
                      if line.lstrip().find('show()')==0: continue
                      print '>>', line,
                      push(line)
                  inFile.close()
              matplotlib.interactive(1)   # turn on interaction
  
  if __name__ == '__main__':
      # Quick sys.argv hack to extract the option and leave filenames in sys.argv.
      # For real option handling, use optparse or getopt.
      if len(sys.argv) > 1 and sys.argv[1]=='-pylab':
          sys.argv = [sys.argv[0]]+sys.argv[2:]
          MatplotLibInterpreter().mainloop()
      else:
          GTKInterpreter().mainloop()
  