Question

I’m trying to make the app read data from a socket, but it takes some time and locks the interface, how do I make it respond to tk events while waiting?

Answer 1

Thats is easy! And you don’t even need threads! But you’ll have to restructure your I/O code a bit. Tk has the equivalent of Xt’s XtAddInput() call, which allows you to register a callback function which will be called from the Tk mainloop when I/O is possible on a file descriptor. Here’s what you need:

from Tkinter import tkinter
tkinter.createfilehandler(file, mask, callback)

The file may be a Python file or socket object (actually, anything with a fileno() method), or an integer file descriptor. The mask is one of the constants tkinter.READABLE or tkinter.WRITABLE. The callback is called as follows:

callback(file, mask)

You must unregister the callback when you’re done, using

tkinter.deletefilehandler(file)

Note: since you don’t know how many bytes are available for reading, you can’t use the Python file object’s read or readline methods, since these will insist on reading a predefined number of bytes. For sockets, the recv() or recvfrom() methods will work fine; for other files, use os.read(file.fileno(), maxbytecount).