Singleton in a DLL?

Question

So i am trying to export somethings in a project to DLL. Anyways a few of the projects use a singleton class very heavily.

template 
class DLL         


        

Answer 1

Please see Multiple Singleton Instances

You will have to ensure that your template instantiation is done in one compilation unit, and you will have to move the pointer = NULL initialization to the CPP file. In other DLLs, you'll have to use extern templates.

Edit: If you are stuck with getting templated singletons to work over multiple DLLs, you could also define a short wrapper function that returns your singleton instance so that the template instantiation is done in one compilation unit only.

Example:

template class Singleton<T>;
__declspec(dllexport/dllimport) T& getInstanceForMyType();
// in the cpp file:
T& getInstanceForMyType()
{
    return Singleton<MyType>::getInstance();
}