英文:
Equivalent of Tuple.Create for Actions and Funcs
问题
.NET 中关于 Tuple 的一个很酷的事情是，你可以这样创建它而不需要输入如下代码：
var x = new Tuple<string, string, int, float, int>("Hi", "Hello", 15, 5.5f, 500);
你可以这样输入：
var x = Tuple.Create("Hi", "Hello", 15, 5.5f, 500);
正确的泛型 Tuple 将会为你创建。
同样的快捷方式对于 Action 和 Func 也很有用。因为似乎对它们不可用，那么如何实现这样的功能，以便不需要输入如下代码：
var x = new Action<string, float, int>((s, f, i) => { /* 做些什么 */ });
或者更糟糕的情况下，这样输入：
var x = new Action<string, float, int>((string s, float f, int i) => { /* 做些什么 */ });
你可以像这样输入：
var x = Action.Create((string s, float f, int i) => { /* 做些什么 */ });
// x 变成了一个 Action<string, float, int>
尽管长度相同，但后一种示例更清晰地显示了参数是什么，总体看起来更整洁。
如何实现这样的扩展方法？请注意，我正在使用 .NET 6.0 和 C# 10.0。
英文:
A cool thing about Tuples in .NET is that instead of typing:
var x = new Tuple<string, string, int, float, int>("Hi", "Hello", 15, 5.5f, 500);
You can type
var x = Tuple.Create("Hi", "Hello", 15, 5.5f, 500);
And the correct generic Tuple will be created for you.
The same shortcut would be beneficial for Actions and Funcs. Since this doesn't seem to be available for them, how would one implement it, so that instead of typing this:
var x = new Action<string, float, int>((s, f, i) => { /* do something */ });
or even worse, this:
var x = new Action<string, float, int>((string s, float f, int i) => { /* do something */ });
you can type something nice like this:
var x = Action.Create((string s, float f, int i) => { /* do something */ });
// x becomes an Action<string, float, int>
Even though the length is the same, the latter example makes what the parameters are more clear, and it looks neater overall.
How can I implement such an extension method? Note that I'm using .NET 6.0 with C# 10.0
答案1
得分: 3
自C# 10起，引入了“自然函数类型”。你甚至不需要这样的方法 - 只需直接编写Lambda表达式并将其分配给一个var，C#可以推断委托的类型。
var action = (string s, float f, int i) => { ... };
请注意，如果参数太多，这不一定是Action。Action类型是有限的，仅支持有限数量的参数。
如果你真的想要一个方法，可以这样做：
var anotherAction = Actions.Create((string s, float f, int i) => { ... });
public static class Actions {
public static T Create<T>(T t) where T : Delegate => t;
}
因为自然函数类型在调用方法时也适用。
英文:
Since C# 10, there are "natural function types". You don't even need such a method - just by writing the lambda directly and assign it to a var, C# can infer the type of the delegate.
var action = (string s, float f, int i) => { ... };
Note that this is not necessarily Action if you have too many parameters. There are only a finite number of Action types, which supports up to a limited number of parameters.
If you really want a method, you can do:
var anotherAction = Actions.Create((string s, float f, int i) => { ... });
public static class Actions {
public static T Create<T>(T t) where T: Delegate => t;
}
because natural function types also work when you call a method.
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