Re: DLL Exports, def files and __declspec(dllexport)

"noemailplease" wrote:


Yes, this what they call name mangling or name decoration. It is
perfectly OK when names get decorated, because the receiving side
knows how to import them. BTW, when you declare a function as
exported, you shoudl do the following macro:

#if define(MY_DLL) // inside the DLL
#define MY_APIEXP __declspec(dllexport)
#else // outside the DLL
#define MY_APIEXP __declspec(dllimport)
#endif

Then declare the function like this:

extern "C" MY_APIEXP int Foo(..);

Define MY_DLL symbol for the DLL project so the macro will expand
to dllexport. No need to define anything for the receiving
project, so macro expands to dllimport.

Now, about name decoration. As long as both sides agree on the
decoration scheme you shouldn't be concerned about that.
However, you need to be very carefull about calling convention and
you must ensure that both sides agree on that. Name decoration
depends on the calling convention used. Each calling convention
has its own name decoration scheme. You must always explicitly
specify calling convention for exported functions and never rely
on default project settings.

Name decoration schemes for C functions are de facto standard, so
no need to worry about compatibility. C++ names decoration is
proprietary for each compiler, that's why C++ exported names are
incompatible between different compilers, or even different
versions of the same compiler.

Here's the explanation of name decoration schemes for C language:

"Name Decoration"
http://msdn.microsoft.com/en-us/library/deaxefa7.aspx

If you absolutely must to supress name decoration for some reason,
then you can use .DEF file where you specify exported names
explicitly regardless of calling convention. However, such
situuation are quite rare.

It seems that your DLL and its client are disagree on function
names. Ensure that you have only one header file that contains
declarations with all proper specifiers (dllexport/import, calling
convention) and use this header both in the DLL and its clients.

HTH
Alex