如何对包装字符串的枚举变体进行模式匹配? [英] How to pattern-match against an enum variant that wraps a String?

问题描述

我有一个枚举:

enum T {
    A(String),
}

我想匹配这个枚举的一个变量，但这段代码不起作用:

I want to match a variable of this enum, but this code doesn't work:

match t {
    T::A("a") => println!("a"),
    T::A("b") => println!("b"),
    _ => println!("something else"),
}

我知道我可以做到这一点，但在我看来它太冗长了:

I understand that I can do this, but it is so verbose in my opinion:

match t {
    T::A(value) => match value.as_ref() {
        "a" => println!("a"),
        "b" => println!("b"),
        _ => println!("something else"),
    },
}

有没有更短的方法来做到这一点?

Is there a shorter way to do this?

推荐答案

我认为唯一的另一种方法是使用 匹配保护，但这与您的嵌套匹配版本一样冗长.

The only other way I think would be to use a match guard, but this is about as verbose as your version with nested matches.

match t {
    T::A(ref value) if value == "a" => println!("a"),
    T::A(ref value) if value == "b" => println!("b"),
    _ => println!("something else"),
}

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