nameof(ArgumentName)

[TonyValenti]

Hi C# Team,
Can you please enable using nameof(ArgumentName) in more places?

Here is what I'd like to do:

public void AddExpression(object? Value, [CallerArgumentExpression(nameof(Value))] string? Key = nameof(Value)) {
}

[CallerArgumentExpression(nameof(Value))] Actually works just fine.
But string? Key = nameof(Value) does not.

[tacosontitan]

I'm curious as to why sizeof works here but nameof doesn't.

Print();
void Print(int size = sizeof(float)) =>
    Console.WriteLine(size);

[CyrusNajmabadi]

sizeof isn't looking up what the name means when it's a primitive type. it just has built in language meaning. nameof(X) has to actually find 'X' in scope to determine if nameof is legal in teh first place. And that 'lookup' has lang-decided rules on which scopes to find the names.

[tacosontitan]

I missed the fact that it was looking at the local scope, my bad :)

[colejohnson66]

It’s interesting that the language rules were changed specifically to allow referencing other parameters, but it doesn’t work outside attributes