Python Cookbook

Module: Building GTK GUIs Interactively

Credit: Brian McErlean

One of Python’s greatest strengths is that it allows you to try things interactively at the interpreter. Tkinter shares this strength, since you can create buttons, windows, and other widgets, and see them instantly on screen. You can click on buttons to activate callbacks and still be able to edit and add to the widgets from the Python command line.

While the Python GTK bindings are generally excellent, one of their flaws is that interactive development is not possible. Before anything is actually displayed, the gtk.mainloop function must be called, ending the possibility of interactive manipulation.

Example 9-1 simulates a Python interpreter while transparently letting the user use GTK widgets without requiring a call to mainloop, which is similar to how Tk widgets work. This version contains enhancements added by Christian Robottom Reis to add readline-completion support.

This program works by running the GTK main loop in a separate thread. The main thread is responsible only for reading lines input by the user and for passing these to the GTK thread, which deals with pending lines by activating a timeout. The resulting program is virtually identical to the Python interpreter, except that there is now no need to call gtk.mainloop for GTK event handling to occur.

Example 9-1. Building GTK GUIs interactively

import _ _builtin_ _, _ _main_ _ import codeop, keyword, gtk, os, re, readline, threading, traceback, signal, ...