See this for detailed tutorial.

Unfortunately, as this project helped me to find out, we can't be more implicit about source generation. Compiler can't run through all usages of LazyshFactory, get all such interfaces and generate lazies for them on demand. It won't work as the C++ templates do. You should always register it with some kind of static compile-time field/attribute/declaration and so on.

If you think it's possible and have some hints on how to do it(how to actually emulate C++ tempaltes in C# source generation + C# generics),

please contact me.