Re: [Mingw-users] Puzzled.

[Franco B. <fra...@we...>]

Am Donnerstag, 15. November 2001 19:43 schrieb Earnie Boyd:
> Yes, but would you export the variable at creation.  Why would you expo=
rt
> an externally declared variable?
>
> It seems right to
>   __declspec(dllexport) char * foo;
> and to later in some other file to
>   __declspec(dllimport) extern char * foo;
> but it seems wrong to
>   __declspec(dllexport) extern char * foo;
> .  It's probably semantics but I'm puzzled.
>
> Earnie.

As long as one uses <C> or <extern "C"> for the symbols, it doesn't matte=
r=20
weather you use __declspec(dllexport) or __declspec(dllimport)

with C++ classes this is different:

in the header :

#ifdef __IN_DLL_ITSELF
#define MYDLLEXP __declspec(dllexport)
#else=20
#define MYDLLEXP __declspec(dllimport)
#endif

class MYDLLEXP foo{
public:
=09foo();
};


when bulding the DLL   __IN_DLL_ITSELF    has to be defined, so when=20
including the header the class is known to be exported form the DLL.

when using the DLL  __IN_DLL_ITSELF must not be defined, so it's clear th=
at=20
the class is imported from a DLL.


Ciao,
  Franco