具有可变参数的函数的委托 [英] A delegate for a function with variable parameters

问题描述

我有这种功能

void func(params object[] parameters) { 
    //Function Body
}

它可以接受以下类型的参数

It can accept parameters of the following sort

func(10, "hello", 30.0);
func(10,20);

等。

我想要为上述功能创建 Action 委托。可能吗？如果不是，为什么？

I wanted to create an Action delegate for the above function. Is it possible? If not then why?

推荐答案

您不能使用现有的 Action 具有 params 的代表，但是您可以这样声明自己的代表：

You can't use the existing Action delegates with params, but you can declare your own delegate that way:

public delegate void ParamsAction(params object[] arguments)

然后：

// Note that this doesn't have to have params, but it can do
public void Foo(object[] args)
{
    // Whatever
}

...

ParamsAction action = Foo;
action("a", 10, 20, "b");

当然，您可以创建 Action< object []> 为您现有的方法-但您失去了它的 params 方面，因为在中没有声明动作< T> 。因此，例如：

Of course you can create an Action<object[]> for your existing method - but you lose the params aspect of it, as that's not declared in Action<T>. So for example:

public static void Foo(params object[] x)
{
}

...

Action<object[]> func = Foo;
func("a", 10, 20, "b"); // Invalid
func(new object[] { "a", 10, 20, "b" }); // Valid

因此，如果您要从代码中调用想要使用 params ，您需要一个在声明中包括该类型的委托类型（按照第一部分）。如果您只想创建一个接受 object [] 的委托，则可以创建<$> $ 的 instance 。 object []> 使用签名中具有 params 的方法-实际上，它只是一个修饰符。

So if you're calling the delegate from code which wants to use params, you need a delegate type which includes that in the declaration (as per the first part). If you just want to create a delegate which accepts an object[], then you can create an instance of Action<object[]> using a method which has params in its signature - it's just a modifier, effectively.

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