Command设计模式3

2014-11-18 星期一 20:44:45 

接下来对struct TestFunctor的泛化，主要是对返回值的返回。分void和非void

1、TestFunctorImpl

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template<typename R> struct Rtraits {     enum{isvoid = false};     typedef R reltype; };   template<> struct Rtraits<void> {     enum{isvoid = true};     typedef void reltype; };   template<typename R, class TList> struct TestFunctorImpl {     typedef R ResultType;     typedef typename         TypeAtNonStrict<TList, 0, NullType>::Result Parm1;       typedef typename         TypeAtNonStrict<TList, 1, NullType>::Result Parm2;       typedef typename Rtraits<R>::reltype reltype;       ResultType operator()(Parm1 p1, Parm2 p2)     {         if(Rtraits<R>::isvoid)         {             printf("TestFunctorImpl::operator(%d, %f) called, return void\n", p1, p2);             return operator_(p1, p2);         }         else         {             printf("TestFunctorImpl::operator(%d, %f) called, return void not\n", p1, p2);                  return operator_(p1,  p2, 1);         }     }     ResultType operator_(Parm1 p1, Parm2 p2)     {         printf("TestFunctorImpl::operator1(%d, %f) called, return void\n", p1, p2);     }     ResultType operator_(Parm1 p1, Parm2 p2, int)     {         printf("TestFunctorImpl::operator1(%d, %f) called, return void not\n", p1, p2);     } };

2、main.cpp

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int main(int argc, char* argv[]) {     TestFunctorImpl<void, TYPELIST_2(int , double)> fImpl;     Functor< void, TYPELIST_2(int , double) > cmdImpl(fImpl);     cmdImpl(5, 5.5);     printf("\n######\n");       TestFunctorImpl<int, TYPELIST_2(int , double)> fImpl_1;     Functor< int, TYPELIST_2(int , double) > cmdImpl_1(fTmpl_1);     cmdImpl_1(5, 5.5);       return 0; }