Listening to changes in a C++ variable from python

[lamthierry at gmail.com]

Let's say I have the following source code in C++:

// The following is in a .cpp file

int val = 0;
for ( int i = 0; i < 10; i++ )
   val = i;


// Now I'm in a python GUI, glade or GTK
Is it possible from the GUI side to listen to changes in the val
variable? Once I notice a change in the variable, I will update a
widget(for example a display progress bar from glade). Any advice or
solutions?