Northik Northik - 3 months ago 33
C++ Question

C++ template for numeric types

I want to have a template to select on numeric types, but I want to also have a global type template too. I tried to apply the solution for this question, but it didn't work:

template<typename T, typename ... Types>
void myFct(T arg1, Types ... rest) { /*do stuff*/ }

template<typename T, typename = typename std::enable_if<std::is_arithmetic<T>::value, T>::type,
typename ... Types>
void myFct(T arg1, Types ... rest) { /* do stuff */ }


because now I have two functions with the same header. What's the right way to do something like:

template<typename T, typename ... Types>
void myFct(T arg1, Types ... rest)
{
if (isNumeric(T))
doNumericStuff();
else
doStuff();
}

Answer

There's probably better ways of doing this, but the simplest way to me is to just slap the enable_if onto the return type:

template<typename T, typename ... Types>
typename std::enable_if<
    std::is_arithmetic<T>::value
>::type
myFct(T arg1, Types ... rest) { /*do numeric stuff*/ }

template<typename T, typename ... Types>
typename std::enable_if<
    !std::is_arithmetic<T>::value
>::type
myFct(T arg1, Types ... rest) { /*do non-numeric stuff*/ }

This gets very unwieldy once you have more than just two mutually exclusive options, but this will definitely work.

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