是否可以声明没有参数的泛型委托？

Question

I have...

Func<string> del2 = new Func<string>(MyMethod);

and I really want to do..

Func<> del2 = new Func<>(MyMethod);

so the return type of the callback method is void. Is this possible using the generic type func?

Answer 1

The Func family of delegates is for methods that take zero or more parameters and return a value. For methods that take zero or more parameters an don't return a value use one of the Action delegates. If the method has no parameters, use the non-generic version of Action :

Action del = MyMethod;

Answer 2

Yes a function returning void (no value) is a Action

public Test()
{
    // first approach
    Action firstApproach = delegate
    {
        // do your stuff
    };
    firstApproach();

    //second approach 
    Action secondApproach = MyMethod;
    secondApproach();
}

void MyMethod()
{
    // do your stuff
}

hope this helps

Answer 3

使用操作委托类型 。

Answer 4

In cases where you're 'forced' to use Func<T> , eg in an internal generic API which you want to reuse, you can just define it as new Func<object>(() => { SomeStuff(); return null; }); .

Answer 5

Here is a code example using Lambda expressions instead of Action/Func delegates.

delegate void TestDelegate();

static void Main(string[] args)
{
  TestDelegate testDelegate = () => { /*your code*/; };

  testDelegate();
}