如何将 Rust 宏变量嵌入到文档中? [英] How to embed a Rust macro variable into documentation?

问题描述

我想在宏生成的文档中使用一个宏变量:

I'd like to use a macro variable in the macro-generated documentation:

macro_rules! impl_foo {
    ($name:ident) => {
        /// Returns a new `$name`.
        fn myfoo() -> $name {

        }
    };
}

但是，变量不会被替换.我也尝试使用 #[doc] 属性:

However, the variable won't be substituted. I also tried using the #[doc] attribute:

macro_rules! impl_foo {
    ($name:ident) => {
        #[doc = concat!("Returns a new `", $name, "`.")]
        fn myfoo() -> $name {

        }
    };
}

这个竟然解析失败:unexpected token: 'concat'

推荐答案

这可以使用递归宏来完成:

This can be done using a recursive macro:

macro_rules! impl_foo {
    ($name:ident, $sname:expr) => {
        #[doc = "Returns a new `"]
        #[doc = $sname]
        #[doc = "`."]
        pub fn myfoo() -> $name {
            42
        }
    };

    ($name:tt) => {
        impl_foo!($name, stringify!($name));
    };
}

impl_foo!(u32);


fn main() {
    println!("Hello, world!");
}

呈现为:

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