简单委托（委托）与多播委托

一尘不染

简单委托（委托）与多播委托

我已经阅读了许多文章，但是我仍然不清楚我们通常创建的普通委托与多播委托之间的区别。

public delegate void MyMethodHandler(object sender);
MyMethodHandler handler = new MyMethodHandler(Method1);
handler += Method2;
handler(someObject);

上面的委托MyMethodHandler将调用这两个方法。现在，多播委托从何而来。我读到它们可以调用多种方法，但恐怕我对委托的基本理解是不正确的。

阅读 277

2020-05-19

共1个答案

一尘不染

本文对此进行了很好的解释：

delegate void Del(string s);

class TestClass
{
    static void Hello(string s)
    {
        System.Console.WriteLine("  Hello, {0}!", s);
    }

    static void Goodbye(string s)
    {
        System.Console.WriteLine("  Goodbye, {0}!", s);
    }

    static void Main()
    {
        Del a, b, c, d;

        // Create the delegate object a that references 
        // the method Hello:
        a = Hello;

        // Create the delegate object b that references 
        // the method Goodbye:
        b = Goodbye;

        // The two delegates, a and b, are composed to form c: 
        c = a + b;

        // Remove a from the composed delegate, leaving d, 
        // which calls only the method Goodbye:
        d = c - a;

        System.Console.WriteLine("Invoking delegate a:");
        a("A");
        System.Console.WriteLine("Invoking delegate b:");
        b("B");
        System.Console.WriteLine("Invoking delegate c:");
        c("C");
        System.Console.WriteLine("Invoking delegate d:");
        d("D");
    }
}
/* Output:
Invoking delegate a:
  Hello, A!
Invoking delegate b:
  Goodbye, B!
Invoking delegate c:
  Hello, C!
  Goodbye, C!
Invoking delegate d:
  Goodbye, D!
*/

2020-05-19