CODEWITHSUNDEEP
c++templatescudapartial-specialization
einpoklum
einpoklum

Reputation: 131525

Double-templated function instantiation fails

The following code:

template<typename T, MyEnum K> __global__ void myKernel(const T a[]);
template<typename T> __global__ void myKernel<T,SomeValueOfMyEnum>(const T a[]) {
    // implementation
}

Triggers the following error message:

error: an explicit template argument list is not allowed on this declaration

Why?

Notes:

Upvotes: 6

Views: 8214

Answers (2)

procr
procr

Reputation: 593

You could use enable_if to achieve the goal.

//template<typename T, MyEnum K> __global__ void myKernel(const T a[]);

template<typename T, MyEnum K>
typename std::enable_if<std::is_same<K, SomeValueOfMyEnum>::value, __global__ void>::type
myKernel<T,SomeValueOfMyEnum>(const T a[]) 
{
     // implementation
}

template<typename T, MyEnum K>
typename std::enable_if<!std::is_same<K, SomeValueOfMyEnum>::value, __global__ void>::type
myKernel<T,SomeValueOfMyEnum>(const T a[]) 
{
     // implementation
}

Upvotes: 2

masoud
masoud

Reputation: 56479

You can't do a partial specialization for a template function, because C++ doesn't define such a thing. You just can do a class template partial specialization [§14.5.5 / temp.class.spec]

Class partial specialization -- A little ugly but maybe it helps you.

enum MyEnum
{
    E1, E2
};

template<typename T, MyEnum K>
struct MyKernel
{
    void operator()(const T a[])
    {
        // ...
    }
};

template<typename T>
struct MyKernel<T, E1>
{
    void operator()(const T a[])
    {
        // ...
    }
};

int main()
{
    MyKernel<int, E1>()( ... ); // <--- To call
}

Upvotes: 7

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