Using Pythonwin in an external project.

Pythonwin is distributed as 2 key components - Pythonwin.exe and win32ui.pyd. Win32ui.pyd contains all the user interface in Pythonwin - Pythonwin.exe is a simple "wrapper" .exe that hosts win32ui.pyd.

This document describes how to imbed the win32ui extension module in your own application.

Limitations.

The biggest limitations you will find are that a host application must

• Have some small changes made to the application source to support win32ui.
• Be an MFC application

Changes to the application.

Subclass a Win32uiHostGlue class

You must sub-class a Win32uiHostGlue class. This class is used as a glue between win32ui.pyd and the host .exe, and is defined in Win32uiHostGlue.h

Currently, this consists of about 5 methods that must be called. The principle is that the Application must hook certain handlers, and delegate them to the HostGlue class. This will ensure the appropriate Win32ui internals are called.

The only documentation for this is below, where Pythonwin's use of this class is described.

Pythonwin.exe architecture

This section describes how Pythonwin.exe implements the above mechanism.

• Add a global variable for the HostGlue instance. i.e.
  // The one and only Glue object.
Win32uiHostGlue NEAR glue;
• Add an InitApplication virtual function. This is very simple. It creates a CDocManager (cant remember exactly why :-), calls the base class implementation. The method in full looks like:
  BOOL CPythonWinApp::InitApplication()
{
m_pDocManager = new CDocManager();
if (!CWinApp::InitApplication())
return FALSE;
if (!glue.DynamicApplicationInit("import startup"))
return FALSE;
return TRUE;
}
Note the "import startup". This is the command that kicks off the entire Pythonwin session. The module startup.py creates the application objects etc.
• Add an InitInstance virtual function. This is very simple. As PythonWin supports both dialog based and MDI applications, the return value of this method is determined by the application window actually created. (As Python code creates the main windows, there is no other way to determine this. The full method is listed below:
  BOOL CPythonWinApp::InitApplication()
{
m_pDocManager = new CDocManager();
if (!CWinApp::InitApplication())
return FALSE;
if (!glue.DynamicApplicationInit("import startup"))
return FALSE;
return TRUE;
}
• And do the same again. There are 4 other methods that require similar treatment. In all cases, the methods call the base class implementation, and delegate off to the HostGlue instance. See pythonwin.cpp for more details.