文档评论

Rust 提供了两种类型的文档注释：内部文档注释和外部文档注释。以下提供各自的实例。

内部文档评论

mod foo {
    //! Inner documentation comments go *inside* an item (e.g. a module or a 
    //! struct). They use the comment syntax //! and must go at the top of the
    //! enclosing item. 
    struct Bar {
        pub baz: i64
        //! This is invalid. Inner comments must go at the top of the struct,
        //! and must not be placed after fields.
    }
}

外部文档评论

/// Outer documentation comments go *outside* the item that they refer to.
/// They use the syntax /// to distinguish them from inner comments.
pub enum Test {
    Success,
    Fail(Error)
}