C#•2mo ago

Is it possible to change the return type of interface method to the type of the implementing struct?

Say I have the following code:

interface IBiggerThan
{
    public abstract IBiggerThan GetBiggest(IBiggerThan compareTo);
}
struct A : IBiggerThan
{
    float _a;
    public A GetBiggest(A compareTo)
    {
        if (this._a > compareTo._a)
            return this;
        return compareTo;
    }
}
struct B : IBiggerThan
{
    float _b;
    public B GetBiggest(B compareTo)
    {
        if (this._b > compareTo._b)
            return this;
        return compareTo;
    }
}

interface IBiggerThan
{
    public abstract IBiggerThan GetBiggest(IBiggerThan compareTo);
}
struct A : IBiggerThan
{
    float _a;
    public A GetBiggest(A compareTo)
    {
        if (this._a > compareTo._a)
            return this;
        return compareTo;
    }
}
struct B : IBiggerThan
{
    float _b;
    public B GetBiggest(B compareTo)
    {
        if (this._b > compareTo._b)
            return this;
        return compareTo;
    }
}

I want to have GetBiggest return an instance of the struct its implemented within. This code obviously won't compile, but I'm wondering if there's a way to implement the intent behind it. I want to avoid returning object or IBiggerThan and then casting it wherever this method gets called, instead I want the return type to explicitly be that of the implementing struct. Is this possible, or am I missing something important?

3 Replies

Sossenbinder•2mo ago

Are you looking for the CRTP by chance? https://blog.stephencleary.com/2022/09/modern-csharp-techniques-1-curiously-recurring-generic-pattern.html

Modern C# Techniques, Part 1: Curiously Recurring Generic Pattern

The curiously recurring generic pattern, where a base type or interface has its derived type as a generic parameter. Part of a series looking at modern C# code techniques.

Evyr•2mo ago

I think so, thanks turns out I went down a similar line to this about 30 minutes ago but misused generics and threw errors

Sossenbinder•2mo ago

Neat. I think it's a good idea in this case anyways, since with a interface-based return type you'll run into boxing behavior when working with structs

Gaming

Programming

Is it possible to change the return type of interface method to the type of the implementing struct?