如何在 CRTP 中调用派生的模板化函数？ [复制]

Question

我的尝试是：

template<typename Derived>
struct Base
{
    void A()
    {
        ((Derived *)this)->B<42>();
    }
};

struct Derived : Base<Derived>
{
    template<int> void B() { }
};

(http://coliru.stacked-crooked.com/a/cb24dd811b562466)

结果

main.cpp: In member function 'void Base<Derived>::A()':
main.cpp:6:34: error: expected primary-expression before ')' token
         ((Derived *)this)->B<42>();
                                  ^
main.cpp: In instantiation of 'void Base<Derived>::A() [with Derived = Derived]':
main.cpp:17:17:   required from here
main.cpp:6:30: error: invalid operands of types '<unresolved overloaded function type>' and 'int' to binary 'operator<'
      ((Derived *)this)->B<42>();
      ~~~~~~~~~~~~~~~~~~~~^~~

Answer 1

您需要keyword template 来调用依赖类型上的模板函数：

((Derived *)this)->template B<42>();
//                 ~~~~~~~~

在模板定义中，template 可用于声明依赖名称是模板。