LDM Notes for September 30th, 2024

[333fred]

https://github.com/dotnet/csharplang/blob/main/meetings/2024/LDM-2024-09-30.md

Agenda

• Extensions

[dersia]

Regarding the this issue, how about supporting this for the underlying type and ext or extension for the extension type?

public extension C for string
{
    public int Length => 10;
    public int M()
    {
        Console.WriteLine(this.Length); // prints the length of the string
        Console.WriteLine(extension.Length); // prints 10
    }
}

Edit: fixed property Length to be non-stateful

[CyrusNajmabadi]

Extensions can't have state. For values there is no place to put them. For reference types, the only option is a conditional week table, which is far too expensive.

If it's a non-stateful property, I don't forsee us ever preferring the extension over the instance. We made a string decision on that with methods and I don't see that changing.

[jnm2]

conditional week table

It might be there all week, and it might not

[TahirAhmadov]

@CyrusNajmabadi where in that question did @dersia say anything about state?
PS. I see what you mean - he wrote int Length { get; } => 10;, but his question is still pertinent if it's int Length => 10;. Care to address the question at hand?

[CyrusNajmabadi]

@CyrusNajmabadi where in that question did @dersia say anything about state?
PS. I see what you mean - he wrote int Length { get; } => 10;, but his question is still pertinent if it's int Length => 10;. Care to address the question at hand?

I literally addressed that in my post. My post covers both non stateful and stateful properties. I was wanting to cover both since a property could be either.

[dersia]

I ment for it to be int Length => 10, thank for correcting @TahirAhmadov

@CyrusNajmabadi so maybe I misunderstood the meeting notes then, I thought this was exactly what was in question in those notes

[qrli]

I don't quite get the motivation to have extension type for this, putting roles aside.
Old extension does not allow members to be shadowed by extensions, which I think is reasonable. Why does the new extension want to allow shadowing underlying type members?