Dynamic DLL linking?

Use LoadLibrary to load the dll. Parse the filename from the path and use that to retrieve the class.

Oh, by the way... all the classes are derived from a basic base class, so don''t worry about fumbling to manage them all...

For example. Let''s say I''ve got a DIRECTX_ENGINE.DLL and an OPENGL_ENGINE.DLL and a SOFTWARE_ENGINE.DLL. They are all derived from the BASE_ENGINE class, which is built-in to the program.


LessBread, thanks for the quick reply!


Some further thought, to retrieve the class in the specific DLL, should all DLLs in question have a function along the lines of...

BASE_ENGINE* CreateMyObject();

... to get the object? Is that a good idea, or is there a better way that comes to your mind?

// Example
BASE_ENGINE* CreateMyObject() {
OPENGL_ENGINE* objRet = new OPENGL_ENGINE();
return objRet;
}

Once I''ve loaded the library, it will behave as though it were a part of the program, right? As far as scope goes?

Do I have to unload the DLL, or will it automatically unload when my program ends?

CreateMyObject() seems like a decent approach to me. To use GetProcAddress on it you''ll have to declare CreateMyObject as "Extern C" - in my experience, GetProcAddress doesn''t play nicely with decorated names. There''s a tut/article here at game dev regarding how to export classes from Dll''s. You might want to look for it and see how it relates to your project. There''s also a similar tut at flipcode - either in the COTD or TOTD archives.

Yes, it''s a good idea to match each call to LoadLibrary with a corresponding call to FreeLibrary. The OS keeps a reference count of loaded dlls and doesn''t unmap those that have outstanding references.