Python Programming On Win32

The PythonWin Object Model

Think of PythonWin as composed of two distinct portions. The win32ui module is a Python extension that provides access to the raw MFC classes. For many MFC objects, there is an equivalent win32ui object. For example, the functionality of the MFC CWnd object is provided by a PyCWnd Python object; an MFC CDocument object by a PyCDocument object, etc. For a full list, see the PythonWin reference (on the PythonWin help menu).

For the MFC framework to be useful, you need to be able to override default methods in the MFC object hierarchy; for example, the method CView::OnDraw() is generally overridden to draw the screen for a view. But the objects exposed by the win32ui module are technically Python types (they aren’t classes) and a quirk in the Python language prevents these Python types from having their methods overridden.

To this end, the win32ui module provides a mechanism to “attach” a Python class instance object to a win32ui type. When MFC needs to call an overridden method, it then calls the method on the attached Python object.

What this means for the programmer is that you can use natural Python classes to extend the types defined in win32ui.

The pywin.mfc package provides Python base classes that interface with many of the win32ui objects. These base classes handle the interaction with win32ui and allow you to use Python subclassing to get your desired behavior.

This means that when you use a PythonWin object, there are two Python objects involved (the ...