Extension wrapper

extension.swift

// exploration
// add a extension wrapper to any type (like `Reactive` from `RxSwift`)
//: Playground - noun: a place where people can play

import UIKit

struct Extension<Base> {
    let base: Base
    init(_ base: Base) {
        self.base = base
    }
}

protocol ExtensionCompatible {
    associatedtype CompatibleType
    static var `extension`: Extension<CompatibleType>.Type { get set }
    var `extension`: Extension<CompatibleType> { get set }
}

extension ExtensionCompatible {
    static var `extension`: Extension<Self>.Type {
        get {
            return Extension<Self>.self
        }
        set {
            // mutate
        }
    }
    
    var `extension`: Extension<Self> {
        get {
            return Extension(self)
        }
        set {
            // mutate
        }
    }
}

extension Extension where Base == Data {
    var blah: String { return "blah" }
}

extension Data: ExtensionCompatible {}

// usage
let data = Data(bytes: [1, 2, 3])
print(data.extension.blah)