ClampedString Property Wrapper

ClampedString.swift

@propertyWrapper
struct ClampedString {
    let max: Int
    var value: String

    init(wrappedValue: String, max: Int) {
        value = wrappedValue
        self.max = max
    }

    var wrappedValue: String {
        get { value }
        set { value = String(newValue.prefix(max)) }
    }
}