铸造委托Func键在C# [英] Cast delegate to Func in C#
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问题描述
我有code:
公共委托INT SomeDelegate(INT P);
公共静态INT公司(INT P){
返回的p + 1;
}
我可以投公司
到 SomeDelegate
或 Func键< INT,INT>
:
SomeDelegate A =公司;
FUNC< INT,INT> B =公司;
但我不能投公司
到 SomeDelegate
和强制转换为 Func键℃后; INT,INT>
有这样的通常方式:
Func键< INT,INT> C =(Func键< INT,INT>)一个; //Сompilation错误
我该怎么办呢?
解决方案
SomeDelegate A =公司;
FUNC< INT,INT> B =公司;
是短期的。
SomeDelegate A =新SomeDelegate(公司); //这里没有投
FUNC< INT,INT> B =新的函数功能:LT; INT,INT>(INC);
您无法施展SomeDelegate的实例函数求< INT,INT>出于同样的原因,你可以不投一个字符串字典< INT,INT> - 他们是不同类型的
。本作品:
Func键< INT,INT> C = X =>斧头);
这是语法糖
类MyLambda
{
SomeDelegate一个;
公共美孚(SomeDelegate一){this.a =一个; }
公众诠释调用(INT X){返回this.a(X); }
}
FUNC< INT,INT> C =新的函数功能:LT; INT,INT>(新MyLambda(一).Invoke);
I have code:
public delegate int SomeDelegate(int p);
public static int Inc(int p) {
return p + 1;
}
I can cast Inc
to SomeDelegate
or Func<int, int>
:
SomeDelegate a = Inc;
Func<int, int> b = Inc;
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
How I can do it?
解决方案
SomeDelegate a = Inc;
Func<int, int> b = Inc;
is short for
SomeDelegate a = new SomeDelegate(Inc); // no cast here
Func<int, int> b = new Func<int, int>(Inc);
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.
This works:
Func<int, int> c = x => a(x);
which is syntactic sugar for
class MyLambda
{
SomeDelegate a;
public Foo(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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