COM Meets Object Pascal
Now that you understand the basic concepts and terms behind COM, ActiveX, and OLE, it's time to discuss how the concepts are implemented in Delphi. This section goes into more detail on COM and gives you a look at how it fits into the Object Pascal language and VCL.
COM defines a standard map for how an object's functions are laid out in memory. Functions are arranged in virtual tables (called vtables)—tables of function addresses identical to Delphi class virtual method tables (VMTs). The programming language description of each vtable is referred to as an interface.
Think of an interface as a facet of a particular class. Each facet represents a specific set of functions or procedures that you can use to manipulate ...