Question

Assuming I have a struct:

struct Vector
{
    public int X, Y;

    // ...
    // some other stuff
}

and a class:

class Map
{
    public Vector this[int i]
    {
        get
        {
            return elements[i];
        }
        set
        {
            elements[i] = value;
        }
    }

    private Vector[] elements

    // ...
    // some other stuff
}

I want to be able to do something like: map[index].X = 0; but I can’t, because the return value is not a variable.

How do I do this, if at all possible?

Answer 1

You should avoid mutable structs.

If you want your type to be mutable use a class instead.

class Vector
{
    public int X { get; set; } // Use public properties instead of public fields!
    public int Y { get; set; }

    // ...
    // some other stuff
}

If you want to use a struct, make it immutable:

struct Vector
{
    private readonly int x;  // Immutable types should have readonly fields.
    private readonly int y;

    public int X { get { return x; }} // No setter.
    public int Y { get { return y; }}

    // ...
    // some other stuff
}