Exporting C++ Object from DLL [closed]

Question

I am creating a wrapper DLL for boost containers (map, vecrtor, set..). In my application, I want to export the C++ object from the DLL to the client. So I am left with two option for exporting:

1. Export the C++ Class using (_declspec)dllexport and use in client.
2. Provide a abstract class with only pure virtual functions (like interfaces in COM) and export only a single method from the DLL (for instance CreateMap).

I am using the containers(map, vector..) extensively in the client.

Can any one please help me, which will be the best method for exporting?

Answer 1

Having C++ classes and STL containers at the DLL interface boundaries is very fragile and highly constraining for your clients: in fact, both the DLL and the client EXEs must be built with the same VC++ compiler version, and dynamically link to the same flavor of the CRT.

It's much safer and better practice to build DLLs exporting a pure C interface. Note that you can use C++ inside the DLL boundaries (this is basically what many Win32 C-interface APIs do).

As an alternative you may export pure C++ abstract classes (interfaces) from the DLL, which is basically what COM does.

You may find this CodeProject article interesting.