可以将方法附加到具有预定义参数的委托吗? [英] Can a method be attached to a delegate with predefined parameters?

问题描述

有时我会遇到必须将方法附加到委托但签名不匹配的情况，例如尝试将 abc 附加到某个字符串参数为hi"的委托.

Sometimes I encounter cases where I have to attach a method to a delegate but the signature doesn't match, like trying to attach abc down there to somedelegate with the string parameter being "hi".

public class test
{
   //...
   public void abc(int i, string x)
   {
      //Do Something
   }
   //...
}
public class test2
{
   somedelegate x;
   //...
   public test2()
   {
      //Do Something
      test y = new test();
      x += y.abc(,"hi");
   }
   delegate void somedelegate(int i);
}

我可以通过创建另一个具有正确签名的委托然后附加它来解决它，但它似乎过于复杂.你能在 C# 中做这样的事情吗?谢谢.

I can work it around by creating another delegate with the correct signature then attaching it but it seems so unnecessarily complex. Can you do something like this in C#? Thanks.

我想最接近我想要实现的是:

I guess there closest to what I wanted to achieve is:

x += (int i) => abc(i, "hi");

推荐答案

是的，你可以用闭包做到这一点

[在 msdn 上有一个很好的主题处理，但就像那里的其他内容一样，很难找到]

[there's a nice treatment of the subject on msdn, but like anything else in there it's hard to find]

大局

• 编写一个可以接受所有你需要的参数的方法
• 在该方法中，您返回一个匿名方法，该方法具有所需的委托目标签名
• 这个方法的调用本身就是委托实例化中的参数

• Write a method that can take all the parameters you need
• Inside that method you return an anonymous method with the delegate-target signature it requires
• This method's call is itself the parameter in the delegate instantiation

是的，这有点像 Matrix-y.但是很酷.

Yes, this is a bit Matrix-y. But way cool.

delegate void somedelegate (int i);

protected somedelegate DelegateSignatureAdapter ( string b, bool yesOrNo, ...) {
    // the parameters are local to this method, so we'll go w/ that.

    // our target delegate requires a single int parameter and void return
    return  (int a) => {
                // your custom code here
                // all calling arguements are in scope - use them as needed

    };  // don't forget the semicolon!
}

// our delegate call
somedelegate myWarpedDelegate = new somedelegate (DelegateSignatureAdapter("someString", true));
myWarpedDelegate (2543);
myWarpedDelegate(15);

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