我试图存储一个指向成员函数模板实例的指针
Derived::initialize
如下(另见
rextester.com
simpler version
问题。):
class Base
{
public:
typedef void (Base::*setterFunction)( unsigned );
template<unsigned N>
struct SetterInterface
{
static Base::setterFunction Function;
};
protected:
template<unsigned N>
void setterImpl( unsigned )
{
}
};
template<unsigned N>
Base::setterFunction Base::SetterInterface<N>::Function = &Base::setterImpl<N>;
class Derived : public Base
{
public:
typedef void (Derived::*Initializer)();
template<typename T , void (T::*F)( unsigned ) >
void initialize()
{
}
template<typename C>
Derived( C* )
{
Initializer initializer = &Derived::initialize<C, C::template SetterInterface<0>::Function>; // NOT OK
//Initializer initializer = &Derived::initialize<C, C::template setterImpl<0> >; // OK
}
};
int main()
{
Derived derived( (Base*)0 );
}
但是我在GCC 5.4.0(和6.4.0)上收到了错误消息
Test.cpp: In instantiation of âDerived::Derived(C*) [with C = Base]â:
Test.cpp:45:28: required from here
Test.cpp:37:39: error: no matches converting function âinitializeâ to type âDerived::Initializer {aka void (class Derived::*)()}â
Initializer initializer = &Derived::initialize<C, C::template SetterInterface<0>::Function>;
^
Test.cpp:30:7: note: candidate is: template<class T, void (T::* F1)(unsigned int)> void Derived::initialize()
void initialize()
问题似乎在于成员函数模板参数,因为
C::template setterImpl<0>
工作,鉴于
C::template SetterInterface<0>::Function
(我想这是前者的别名)不是。例如:
Base::setterFunction f1 = &Base::setterImpl<0>;
Base::setterFunction f2 = Base::template SetterInterface<0>::Function;