CompuServe Messages

Hi Michael, > Concievably, you could rebuild MFC and _export all of the classes, > and then you would be able to export derived classes. But, > unfortunately, MS says this is a no go. In fact as you have noticed > they manually _export member functions by ordinal number. I don't > know of a good solution other than to look at some alternative to > exporting the classes. PMJI, I know MFC TechNote #33 doesn't go into a lot of Detail as to why "class _export" syntax was not used for MFC250x.DLL. It states: Using "class _export" may be a viable alternative for building smaller DLLs, but in the case of a large DLL like MFC, the default exporting mechanism has efficiency and capacity limits. The efficiency limit is the function name lookup speed. A function can be found in a DLL's exported names table much more quickly if it is exported by ordinal rather than by name (note that the "class _export" syntax exports member functions by name). The capacity limit is referring to the 64K limit on a module's resident name table. If all of the MFC classes were exported using "class _export" syntax then the name table would be filled beyond capacity. Best Regards, Don Schmitt Microsoft Developer Support