Set-only subscripts

Evolution Pitches
12

Question to the language experts: Would this feature also allow for inout parameters in subscripts?

struct S {
  static subscript <T>(value: inout T) -> T {
    set {
      value = newValue
    }
  }
}

Not by the proposal implementation itself, but as some followup feature.

I would need a combination of the pitched feature and the above:

public subscript (context: Context, storage: Storage) -> Value {
  get {
    storage.value
  }
}

public subscript (context: Context, storage: inout Storage) -> Value {
  set {
    storage.value = newValue
  }
}

This would allow a nice optimization for property wrappers on value types, while keeping the design nearly the same for reference types. :+1:

If the answer to the above question is 'Yes' then I think it's another good motivation for this proposal. :wink:

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