CODEWITHSUNDEEP
c++templatesinline
Nodera
Nodera

Reputation: 11

Inline function as template argument, without using function pointer

I'm developing an object Foo, which have several member variables and one major member function bar().

template<typename T>
Foo
{
public:
    T bar()
    {
       ...
       return m_a + myfunction(m_b);
    }

private :
    T m_a, m_b;
};

At the moment myfunction is another member function. But I would like to be able to write a main like this :

float newfunction(float) {....}

void main()
{
    Foo<float, newfunction> foo;
    float result = foo.bar();
}

And so, newfunction would be used inline in bar() instead of myfunction. I don't want to use a function pointer for performance purpose : bar() use openMP and myfunction() is designed to be called thousands times per second by each core of the cpu. And so I think that in this condition, my function must be inline and I must not use a pointer. And newfunction is a simple function, with a really low computational cost.

Upvotes: 1

Views: 1208

Answers (1)

Some programmer dude
Some programmer dude

Reputation: 409482

If you only use newfunction in the Foo::bar function, then I suggest you pass it as an argument to the bar function instead:

template<typename T>
struct Foo
{
    template<typename F>
    T bar(F func)
    {
        return m_a + func(m_b);
    }

    T m_a, m_b;
};

Then you can call it like

Foo<float> foo;
float result = foo(newfunction);

If on the other hand you need to store the function to be used in multiple member functions of Foo I recommend you read about std::function.

Then you can do something like

template<typename T>
struct Foo
{
    Foo(std::function<T(T)>& func)
        : m_function(func)
    {}

    T bar()
    {
        return m_a + m_function(m_b);
    }

    T m_a, m_b;
    std::function<T(T)> m_function;
};

To be used as

Foo<float> foo(newfunction);
float result = foo.bar();

Upvotes: 2

Related Questions