Last edit: 05-03-17 Graham Wideman

Delphi

Introduction

The GWRefCt provides a quick way to verify our understanding of the use and behavior of COM object references in different Delphi scenarios. It has a main window that displays some demo code, and buttons to allow you to step through the code while watching the effects on COM objects in the monitor window. It is a bit like the Delphi debugger, but not nearly as smart... but it does the job for our purposes.  You can, of course, run the demo in the Delphi debugger for even more detail.

A number of demonstrations (corresponding to individual demo units) are included, and you can add more if you want. Demos include:

• Basics: How adding and removing references in different ways impacts RefCount
• Passing COM references TO procedures and functions
• Passing COM references FROM procedures and functions
• Special case of passing COM references to Windows API.

Instructions

Adding More Demos

You add more demos by adding one or more units to the application and recompiling.   Start by copying the GWCOMDemo_Basic.pas unit as an example. Note that each additional unit has initialization code to add it to the demos that the app knows about, so no need to modify anything in the app to run your added demos.

Copyright Status

Please feel free to distribute or publish this article and associated code, provided some note of credit for me remains attached. Permission is also granted to include this article on CDROM collections, again provided credit remains attached. Thanks!

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