单例关闭修改开放扩展

Posted 2023-03-15

【中文标题】单例关闭修改开放扩展

【英文标题】：Singleton closed for modification open to extend

【发布时间】：2018-02-02 11:05:10

【问题描述】：

我想知道如何做到这一点： 假设我有一个单例类

class Global
    static let shared = Global()
    private init()

我希望此类禁止修改。但开放扩展。 我想达到的结果 Global.shared.var1

当var1 来自另一个类时，会以某种方式扩展Global。

这是一个愿望。甚至可能吗？实现这一目标的正确方法是什么。

【参考方案1】：

找到了一个暂时满足我目的的 hack（建议我更好的方法/替代方法）：

class Students
    static let shared = Students()
    private init()
    var name: [String] = ["Farhan","Hasan","Saba","Fatima"]

class Teachers
    static let shared = Teachers()
    private init()
    var name: [String] = ["Mr. Riaz","Ms. Ayesha"]


//Base for Singleton, sort of proxy
class Global
    private init()


//Somewhere else in your project
extension Global
    static let students = Students.shared

//Somewhere else in your project
extension Global
    static let teachers = Teachers.shared


//Apparently it served the purpose
print(Global.students.name) //prints: ["Farhan", "Hasan", "Saba", "Fatima"]
print(Global.teachers.name) //prints: ["Mr. Riaz", "Ms. Ayesha"]