同じ条件で一連のstd :: conditionalを書く

Question

もっとコンパクトな方法はありますか？条件が同じで、異なる線用type_Ax、type_Bx、type_Cxが異なる

typedef typename std::conditional< condition, type_A1, type_B1 > type_C1; 
typedef typename std::conditional< condition, type_A2, type_B2 > type_C2; 
typedef typename std::conditional< condition, type_A3, type_B3 > type_C3; 
... 

。

Answer 1

template<class A, class B> using select = std::conditional_t<condition, A, B>; 

using C1 = select<A1, B1>; // or typedef if you really like that syntax 
// etc.