It's most certainly not: - you have to at least implement the destructor if you are going to use the abstract class across multiple DLLs - else, dynamic_cast w

It's most certainly not: - you have to at least implement the destructor if you are going to use the abstract class across multiple DLLs - else, dynamic_cast won't work since each DLL may have its own type_info object for the abstract class - even if a method is marked abstract, it can still have a default implementation: https://gcc.godbolt.org/z/bAE7v6 https://gcc.godbolt.org/z/bAE7v6 though other prominent OO languages are slowly catching up with this ;)