Multiple SFINAE rules
- by Fred
Hi everyone,
After reading the answer to this question, I learned that SFINAE can be used to choose between two functions based on whether the class has a certain member function. It's the equivalent of the following, just that each branch in the if statement is split into an overloaded function:
template<typename T>
void Func(T& arg)
{
if(HAS_MEMBER_FUNCTION_X(T))
arg.X();
else
//Do something else because T doesn't have X()
}
becomes
template<typename T>
void Func(T &arg, int_to_type<true>); //T has X()
template<typename T>
void Func(T &arg, int_to_type<false>); //T does not have X()
I was wondering if it was possible to extend SFINAE to do multiple rules. Something that would be the equivalent of this:
template<typename T>
void Func(T& arg)
{
if(HAS_MEMBER_FUNCTION_X(T)) //See if T has a member function X
arg.X();
else if(POINTER_DERIVED_FROM_CLASS_A(T)) //See if T is a pointer to a class derived from class A
arg->A_Function();
else if(DERIVED_FROM_CLASS_B(T)) //See if T derives from class B
arg.B_Function();
else if(IS_TEMPLATE_CLASS_C(T)) //See if T is class C<U> where U could be anything
arg.C_Function();
else if(IS_POD(T)) //See if T is a POD type
//Do something with a POD type
else
//Do something else because none of the above rules apply
}
Is something like this possible?
Thank you.
