On Thursday, 8 November 2012 at 17:27:42 UTC, Tommi wrote:
..and it got me thinking, couldn't we just get rid of dynamic polymorphism and classes altogether? Doesn't static polymorphism through the use of duck typing and member function delegates provide all that we need?
For a lot of programs (or parts of programs) that currently use runtime polymorphism, the answer seems to be yes, and Phobos is very good at helping D programmers do their polymorphism at compile-time.
But dynamic polymorphism is special in that it is just that - dynamic.
You can decide which implementation to use at runtime rather than having to do it at compile-time. When this runtime component is necessary, there is no replacement for runtime polymorphism.
As for function pointers and delegates, class-based polymorphism provides a couple of additional niceties: for one, vtables are created at compile-time. Secondly, it provides a lot of syntax and structure to the system that you don't have with arbitrary function pointers or delegates.
Emulating OOP (no, not Object *Based* Programming) with function pointers is a real pain. Without classes, we'd only be marginally better off than C in this area, thanks to delegates.
