Metaprogramming in C++ and in D

Question

The template mechanism in C++ only accidentally became useful for template metaprogramming. On the other hand, D\'s was designed specifically to facilitate this. And apparently

Answer 1

in D you can check the size of a type and the available methods on it and decide which implementation you want to use

this is used for example in the core.atomic module

bool cas(T,V1,V2)( shared(T)* here, const V1 ifThis, const V2 writeThis ){
    static if(T.sizeof == byte.sizeof){
       //do 1 byte CaS
    }else static if(T.sizeof == short.sizeof){
       //do 2 byte CaS
    }else static if( T.sizeof == int.sizeof ){
       //do 4 byte CaS
    }else static if( T.sizeof == long.sizeof ){
       //do 8 byte CaS
    }else static assert(false);
}