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我想写一个包装函数,它在编译时链接到一个函数指针,因此我写了下面的代码,它在C++ 11中工作得很好:decltype成员函数指针作为模板参数在c + + 11
#include <iostream>
template<typename Fn, Fn func, typename... Args>
typename std::result_of<Fn(Args...)>::type callfunc(Args&&... args){
//do something else here
return (*func)(args...);
}
double add(double a, double b){
return a+b;
}
int main(){
std::cout << callfunc<decltype(&add), &add>(2.0, 3.0) << "\n";
}
但是,如果我尝试做同样的事情,像这样
#include <iostream>
template<typename Fn, Fn func, typename... Args>
typename std::result_of<Fn(Args...)>::type callfunc(Args&&... args){
//do something else here
return (*func)(args...);
}
class testclass {
public:
double testadd(double a, double b);
void run();
};
double testclass::testadd(double a, double b){
return a+b;
}
void testclass::run(){
std::cout <<
callfunc<decltype(&testclass::testadd), &testclass::testadd>(2.0, 3.0)
// ^^^^^ this won't compile! ^^^^
<< "\n";
}
int main(){
testclass obj;
obj.run()
}
我得到以下编译器错误的成员函数:
error: indirection requires pointer operand ('double (testclass::*)(double,double)' invalid) return (*func)(args...);
我做错了什么?