WFC Technical Note 006 - Using MFC-Based DLLs

$Revision: 1 $ Last Modified $Date: 4/16/00 6:28a $

Introduction

Microsoft Foundation Classes (MFC) is a nice framework for creating GUIs. It excels at creating dialog boxes that get information from the user. This technote shows you how to use MFC to do the grunt work of GUI code without having to base your entire program on MFC.

A Scenario

Many times, I like to put GUIs in their own DLL. This allows me to isolate that code for easy maintenance as well as easy upgrades. If I want to totally change a dialog box, I don't have to recompile the entire product. Just replace that one DLL. Typically, I will have a DLL name and a function name in my main program. When it is time to display the dialog, I will call LoadLibrary() to load the DLL, then call GetProcAddress() to get the address of the function. This, in essence, is what COM/OLE does when you instantiate a COM object (via CoCreateInstance()).

Code

It is amazingly simple to do this. All you need to know is the magic functions to call. Here's a sample of a function that can be manually loaded as described in the scenario above:

BOOL __stdcall IsItOKToContinue( void )
{
   AFX_MANAGE_STATE( AfxGetStaticModuleState() );

   CContinueDialog dialog( AfxGetMainWnd() );

   return( ( dialog.DoModal() == IDOK ) ? TRUE : FALSE );
}

Samuel R. Blackburn