[fpc-devel] VMT compatibility

Alexey Barkovoy clootie at ixbt.com
Sat Jan 29 23:50:58 CET 2005

>>> I where any chance to see FreePascal generating VMT's for classes that is 
>>> more compatible with C++ / TurboPascal / Delphi one?
>>> To explain mine question: recently I've been porting Delphi framework 
>>> interfacing to C++ code to FPC and finded out that althrow Delphi VMT layout 
>>> is compatible to C++ one, FPC is not.
>> Are you sure Delphi is compatible to "C++" or just to Borland C++? The latter 
>> would be logical, since both Delphi and C++ Builder use the same backend. Or 
>> are Delphi classes also binary compatible with Visual C++ and g++ classes?
> Delphi is compatible at least with Borland C++ and MS VC++. And taking in 
> accout how COM intefaces are implemented in C++ (I'm supposing here all C++ 
> compilers support the same syntax) - each C++ compiler supporting MS way to 
> declare COM interfaces has compatible VMT layout.

PS. I'm not insisting for compatibility on "internal" fields (with negative 
offset in Delphi case), but hope for layout compatibility of user defined 
virtual methods. 

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