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F
The COM in
Practice
In this appendix, we provide a very brief review of the component object
model (COM) used by Microsoft’s multimedia and graphics program devel-
opment environments.
F. 1 U s i n g C O M
As we said in Chapter 12, COM is architecture-neutral. It is a binary stan-
dard with a predefined layout for the interfaces a COM object exposes to the
outside world; the objects themselves never appear externally. Most COM
CoClasses and their interfaces are implemented in C++. The CoClass is just
a class (because the COM object itself is never exposed, it can be described
in a language-specific way) and a C++ abstract class is perfect for the job. In-
terfaces are tables of pointers to functions implemented by the COM object.
The table represents ...