👔NonNominalTypeWrapper

👔 NonNominalTypeWrapper

💾 程式：paiza.io ⬆️ 需要： HasMirrors

// --------------------------------
//     ⭐ NonNominalTypeWrapper
// --------------------------------

/// non-nominal type: 
/// ⛔ - can't be extended. 
/// ⛔ - can't conform to protocols.
/// use this type to wrap non-nominal types, so they can do these things.
public struct NonNominalTypeWrapper<T> {
    let subject: T     // T is non-nominal (i.e. Any, Tuple)
}

/// convenience init
/// usage: `NonNominalTypeWrapper(instance)`
extension NonNominalTypeWrapper {
    // ⭐ 注意：這裡不能寫成 init<T>
    // 不然會引進「新的型別參數 `T`」（是的，跟「舊的型別參數 `T`」
    // 名字一模一樣），然後產生「令人傻眼的錯誤訊息」：
    // 「⛔ cannot assign value of type 'T' to type 'T'」
    public init(_ subject: T){
        self.subject = subject
    }
}

/// ⭐ custom extension (Loggable conformance)
extension NonNominalTypeWrapper: Loggable {

    @discardableResult
    public func log() -> Self { 
        print(String(describing: self.subject)) 
        return self 
    }
    
    @discardableResult
    public func reflect() -> Self { 
        print(String(reflecting: self.subject))
        return self 
    }
    
    // mirror (object tree)
    @discardableResult
    public func mirror() -> Self {
        mirrorChildren(of: self.subject)
    }
}

💈範例

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