C# 嵌套类/结构可见性

Question

我试图弄清楚实现特定 API 目标的正确语法是什么，但我在可见性方面苦苦挣扎。

我希望能够访问 Messenger 实例的成员，例如 msgr.Title.ForSuccesses。

但是，我不希望能够从我的 Messenger 类之外实例化 Messenger.Titles。

我也愿意将 Messenger.Titles 变成一个结构体。

我猜我需要某种工厂模式或其他东西，但我真的不知道该怎么做。

见下文:

class Program {
    static void Main(string[] args) {
        var m = new Messenger { Title = { ForErrors = "An unexpected error occurred ..." } }; // this should be allowed
        var t = new Messenger.Titles(); // this should NOT be allowed
    }
}

public class Messenger {
    // I've tried making this private/protected/internal...
    public class Titles {
        public string ForSuccesses { get; set; }
        public string ForNotifications { get; set; }
        public string ForWarnings { get; set; }
        public string ForErrors { get; set; }

        // I've tried making this private/protected/internal as well...
        public Titles() {}
    }

    public Titles Title { get; private set; }
    public Messenger() {
        Title = new Titles();
    }
}

Answer 1

您只需要将 Titles 设为私有(private)并公开一个接口(interface)而不是它。

class Program {
    static void Main(string[] args) {
        var m = new Messenger { Title = { ForErrors = "An unexpected error occurred ..." } }; // this is allowed
        var t = new Messenger.Titles(); // this is NOT allowed
    }
}

public class Messenger {
    public interface ITitles {
        string ForSuccesses { get; set; }
        string ForNotifications { get; set; }
        string ForWarnings { get; set; }
        string ForErrors { get; set; }
    }

    private class Titles : ITitles {
        public string ForSuccesses { get; set; }
        public string ForNotifications { get; set; }
        public string ForWarnings { get; set; }
        public string ForErrors { get; set; }
    }

    public ITitles Title { get; private set; }
    public Messenger() {
        Title = new Titles();
    }
}