CODEWITHSUNDEEP
c++functiontemplates
tesla1060
tesla1060

Reputation: 2765

c++ how to pass min() and max() as as constructor argument?

I have a class MyClass, which will use either min() or max() based on what argument is taken during construction,

class MyClass {
private:
    myfunc;
public:
    MyClass(args);
}

Later myfunc will be used in another method in MyClass, and I would like args can be used to initialize myfunc to be either max or min, wondering how to achieve that? or maybe other way I can set myfunc to be either max or min will be fine too.

Upvotes: 1

Views: 522

Answers (1)

Soonts
Soonts

Reputation: 21936

I would do it like this:

class MyClass
{
    const bool isMax;

public:
    MyClass( bool ax ) : isMax( ax ) { }

    template<class E>
    E apply( E a, E b ) const
    {
        if( isMax )
            return std::max( a, b );
        else
            return std::min( a, b );
    }
};

Technically doable with a function pointer, or std::function, however these are probably slower. They compile into indirect jumps. This version compiles into a regular branch. Because the flag never changes, from the CPU’s point of view the outcome is very predictable.

Upvotes: 3

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