Re: C++ vs D: Default param values and struct to array casting

[Paul Backus via Digitalmars-d-learn]

On Friday, 6 September 2019 at 09:28:57 UTC, Andrew Edwards wrote:
This is my thought on how to accomplish op overloading:
struct Test
{
    float a, b, c, d;
    float opIndex(size_t i)
    in(i >= 0 && i <= 3)
    {
        final switch(i)
        {
            case 0: return a;
            case 1: return b;
            case 2: return c;
            case 3: return b;
        }
    }

    void opIndexAssign(float val, size_t i)
    in(i >= 0 && i <= 3)
    {
        final switch(i)
        {
            case 0: a = val; break;
            case 1: b = val; break;
            case 2: c = val; break;
            case 3: d = val; break;
        }
    }
}

Please advise if I've gone off the beaten path. It seems 
overkill for the two lines of code C++ requires so any 
suggestion is greatly appreciated.

You can use `static foreach` to eliminate the repetition in the 
switch statements. For example:

float opIndex(size_t i)
    in (i < typeof(this).tupleof.length)
{
    final switch (i) {
        static foreach (fid, field; typeof(this).tupleof) {
            case fid: return field;
        }
    }
}