Re: How to reinvent (and improve) Microsoft Message Maps?

Hi,

Here is my grain of salt on the topic. The message map macros
generates a C array of a structure containing, among other things, the
message define and a member function pointer (very interesting hack
BTW where inside the dispatcher, a typecast is perfomed on the pointer
depending on the function signature associated with a given message).
Also, each message map is linked to the base class message map. The
CWindow dispatcher then perform a linear search on these C arrays to
find the correct entry starting from the leaf classe map and going up
in the hierarchy until a match is found. Microsoft has optimized the
search by writting an assembler version of the search function.
Another optimization they have done is to have a cache containing the
mose recent seen messages. If the dispatcher finds the current message
in the cache, it will totally skip the message map search. The cache
is certainly something that you want to keep in your design.

What you could do to do better than MS, IMO it would be to place map
entry in a sorted vector and do a binary seach in the dispatcher. If
you are looking for a sorted vector class, you should check Mr.
Alexandrescu Loki library as it contains such a class using a regular
STL vector.