Martin v. Löwis wrote: >Before trying to explain the reason, please try to explain the >problem first. What is it *really* that you want to do which >you feel you currently can't do? > > Probably I should have started the discussion with this; sorry if I confused everybody. But here it is:
I have an extension module for scientific visualization. This extension module opens one or more windows, in which plots can be made. Something similar to the plotting capabilities of Matlab. For the graphics windows to remain responsive, I need to make sure that its events get handled. So I need an event loop. At the same time, the user can enter new Python commands, which also need to be handled. To achieve this, I make use of PyOS_InputHook, a pointer to a function which gets called just before going into fgets to read the next Python command. I use PyOS_InputHook to enter an event loop inside my extension module. This event loop handles the window events, and returns as soon as a new Python command is available at stdin, at which point we continue to fgets as usual. While this approach more or less works, there are two problems that I have run into: 1) What if the user decides to import Tkinter next? Tkinter notices that PyOS_InputHook is already set, and does not reset it to its own event loop. Hence, Tkinter's events are not handled. Similarly, if a user imports Tkinter before my extension module, I don't reset PyOS_InputHook, so Tkinter's events are handled but not mine. If I were to reset PyOS_InputHook to my extension module's event loop, then my events get handled but not Tkinter's. 2) On Windows, many users will use IDLE to run Python. IDLE uses two Python threads, one for the GUI and one for the user's Python commands. Each has its own PyOS_InputHook. If I import my extension module (or Tkinter, for that matter), the user-Python's PyOS_InputHook gets set to the corresponding event loop function. So far so good. However, PyOS_InputHook doesn't actually get called: Between Python commands, the GUI-Python is waiting for the user to type something, and the user-Python is waiting for the GUI-Python. While the user-Python is waiting for the GUI-Python thread, no call is made to PyOS_InputHook, therefore we don't enter an event loop, and no events get handled. Hence, neither my extension module nor Tkinter work when run from IDLE. --Michiel. -- Michiel de Hoon Center for Computational Biology and Bioinformatics Columbia University 1150 St Nicholas Avenue New York, NY 10032 _______________________________________________ Python-Dev mailing list Python-Dev@python.org http://mail.python.org/mailman/listinfo/python-dev Unsubscribe: http://mail.python.org/mailman/options/python-dev/archive%40mail-archive.com
