Re: fuction Return function

[Meta via Digitalmars-d-learn]

On Saturday, 26 July 2014 at 20:49:30 UTC, seany wrote:

Can a function return a function in D? Sorry if i missed the answer somewhere

Yup, you can return functions, delegates, or function pointers.

int function(int) returnsFunc1()
{
        return function(int n) { return n; };
}

int function(int) returnsFunc2()
{
        //Even works for nested functions.
        //Make them static so they don't
        //create a context pointer to
        //returnsFunc2's frame
        static int fun(int n)
        {
                return n;
        }
        
        return &fun;
}

int test(int n)
{
        return n;
}

int function(int) returnsFunc3()
{
        return &test;
}

int delegate(int) makeAdder(int numToAdd)
{
        return delegate(int n) { return n + numToAdd; };
}

void main()
{
        auto func1 = returnsFunc1();
        assert(func1(1) == 1);
        
        auto func2 = returnsFunc2();
        assert(func2(2) == 2);
        
        auto func3 = returnsFunc3();
        assert(func3(3) == 3);
        
        auto add3 = makeAdder(3);
        assert(add3(1) == 4);
}