How to expose STL list over DLL boundary?

You can pass stl objects between DLLs and support different compilers if you are careful where you instantiate each stl type. You need some intelligent "DLLEXPORT" macros -- I use the following set to successfully support VC and gcc.

#ifdef WIN32
#ifdef MYDLLLIB_EXPORTS      // DLL export macros
#define MYDLLLIB_API __declspec(dllexport)
#define MYDLLLIB_TEMPLATE
#else
#define MYDLLLIB_API __declspec(dllimport)
#define MYDLLLIB_TEMPLATE extern
#endif
#else                       // Not windows --- probably *nix/bsd
#define MYDLLLIB_API
#ifdef MYDLLLIB_EXPORTS
#define MYDLLLIB_TEMPLATE
#else
#define MYDLLLIB_TEMPLATE extern
#endif
#endif // WIN32

When compiling your DLL, define MYDLLLIB_EXPORTS. In the DLL you can then instantiate each stl type you wish to use, for example, lists or vectors of strings

MYDLLLIB_TEMPLATE template class MYDLLLIB_API std::vector<std::string>;
MYDLLLIB_TEMPLATE template class MYDLLLIB_API std::list<std::string>;

Consumers of your DLL (who don't have MYDLLLIB_EXPORTS defined) will then see

extern template class __declspec(dllimport) std::vector<std::string>;

and use the binary code exported from your DLL instead of instantiating their own.

Perhaps you can pass something like "handles" to list/deque iterators? These handle types would be opaque and declared in a header file you would ship to the users. Internally, you would need to map the handle values to list/deque iterators. Basically, the user would write code like:

ListHandle lhi = GetListDataBegin();
const ListHandle lhe = GetListDataEnd();

while (lhi != lhe)
{
  int value = GetListItem(lhi);
  ...
  lhi = GetNextListItem(lhi);
}