Detect if class has overloaded function fails on Comeau compiler
- by Frank
Hi Everyone,
I'm trying to use SFINAE to detect if a class has an overloaded member function that takes a certain type. The code I have seems to work correctly in Visual Studio and GCC, but does not compile using the Comeau online compiler.
Here is the code I'm using:
#include <stdio.h>
//Comeau doesnt' have boost, so define our own enable_if_c
template<bool value> struct enable_if_c { typedef void type; };
template<> struct enable_if_c< false > {};
//Class that has the overloaded member function
class TestClass
{
public:
void Func(float value) { printf( "%f\n", value ); }
void Func(int value) { printf( "%i\n", value ); }
};
//Struct to detect if TestClass has an overloaded member function for type T
template<typename T>
struct HasFunc
{
template<typename U, void (TestClass::*)( U )> struct SFINAE {};
template<typename U> static char Test(SFINAE<U, &TestClass::Func>*);
template<typename U> static int Test(...);
static const bool Has = sizeof(Test<T>(0)) == sizeof(char);
};
//Use enable_if_c to only allow the function call if TestClass has a valid overload for T
template<typename T> typename enable_if_c<HasFunc<T>::Has>::type CallFunc(TestClass &test, T value) { test.Func( value ); }
int main()
{
float value1 = 0.0f;
int value2 = 0;
TestClass testClass;
CallFunc( testClass, value1 ); //Should call TestClass::Func( float )
CallFunc( testClass, value2 ); //Should call TestClass::Func( int )
}
The error message is: no instance of function template "CallFunc" matches the argument list. It seems that HasFunc::Has is false for int and float when it should be true.
Is this a bug in the Comeau compiler? Am I doing something that's not standard? And if so, what do I need to do to fix it?
