本文介绍了在 C# 中将委托强制转换为 Func的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有代码:
public delegate int SomeDelegate(int p);
public static int Inc(int p) {
return p + 1;
}
我可以将 Inc
转换为 SomeDelegate
或 Func:
I can cast Inc
to SomeDelegate
or Func<int, int>
:
SomeDelegate a = Inc;
Func<int, int> b = Inc;
但我不能将 Inc
转换为 SomeDelegate
并在转换为 Func<int, int>
之后使用通常的方式如下:
but I can't cast Inc
to SomeDelegate
and after that cast to Func<int, int>
with usual way like this:
Func<int, int> c = (Func<int, int>)a; // Сompilation error
我该怎么做?
推荐答案
SomeDelegate a = Inc;
Func<int, int> b = Inc;
简称
SomeDelegate a = new SomeDelegate(Inc); // no cast here
Func<int, int> b = new Func<int, int>(Inc);
您不能将 SomeDelegate 的实例强制转换为 Func<int, int>出于同样的原因,您不能将字符串转换为 Dictionary<int, int>-- 它们是不同的类型.
You can't cast an instance of SomeDelegate to a Func<int, int> for the same reason you can't cast a string to a Dictionary<int, int> -- they're different types.
这行得通:
Func<int, int> c = x => a(x);
这是语法糖
class MyLambda
{
SomeDelegate a;
public MyLambda(SomeDelegate a) { this.a = a; }
public int Invoke(int x) { return this.a(x); }
}
Func<int, int> c = new Func<int, int>(new MyLambda(a).Invoke);
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