From d1e3898bd5d830c29602067ffdb87639f99f0862 Mon Sep 17 00:00:00 2001 From: Alexis Bourget Date: Fri, 29 May 2020 23:41:46 +0200 Subject: [PATCH] Added the documentation for the 'use' keyword --- src/libstd/keyword_docs.rs | 58 ++++++++++++++++++++++++++++++++++++-- 1 file changed, 56 insertions(+), 2 deletions(-) diff --git a/src/libstd/keyword_docs.rs b/src/libstd/keyword_docs.rs index 6fbb0139b0e..f74ee6a3e9b 100644 --- a/src/libstd/keyword_docs.rs +++ b/src/libstd/keyword_docs.rs @@ -1213,9 +1213,63 @@ mod unsafe_keyword {} // /// Import or rename items from other crates or modules. /// -/// The documentation for this keyword is [not yet complete]. Pull requests welcome! +/// Usually a `use` keyword is used to shorten the path required to refer to a module item. +/// The keyword may appear in modules, blocks and even functions, usually at the top. +/// +/// The most basic usage of the keyword is `use path::to::item;`, +/// though a number of convenient shortcuts are supported: +/// +/// * Simultaneously binding a list of paths with a common prefix, +/// using the glob-like brace syntax use `a::b::{c, d, e::f, g::h::i};` +/// * Simultaneously binding a list of paths with a common prefix and their common parent module, +/// using the [`self`] keyword, such as `use a::b::{self, c, d::e};` +/// * Rebinding the target name as a new local name, using the syntax `use p::q::r as x;`. +/// This can also be used with the last two features: `use a::b::{self as ab, c as abc}`. +/// * Binding all paths matching a given prefix, +/// using the asterisk wildcard syntax `use a::b::*;`. +/// * Nesting groups of the previous features multiple times, +/// such as `use a::b::{self as ab, c, d::{*, e::f}};` +/// * Reexporting with visibility modifiers such as `pub use a::b;` +/// * Importing with `_` to only import the methods of the item without binding it to a name +/// (to avoid conflict for example): `use ::std::io::Read as _;`. +/// +/// Using path qualifiers like [`crate`], [`super`] or [`self`] is supported: `use crate::a::b;`. +/// +/// Note that when the wildcard `*` is used on a type, it does not import its methods (though +/// for `enum`s it imports the variants, as shown in the example below). +/// +/// ```compile_fail +/// # fn main() { +/// enum ExampleEnum { +/// VariantA, +/// VariantB, +/// } /// -/// [not yet complete]: https://github.com/rust-lang/rust/issues/34601 +/// impl ExampleEnum { +/// fn new() -> Self { +/// Self::VariantA +/// } +/// } +/// +/// use ExampleEnum::*; +/// +/// // Compiles. +/// let _ = VariantA; +/// +/// // Does not compile ! +/// let n = new(); +/// # } +/// ``` +/// +/// For more information on `use` and paths in general, see the [Reference]. +/// +/// The differences about paths and the `use` keyword between the 2015 and 2018 editions +/// can also be found in the [Reference]. +/// +/// [`crate`]: keyword.crate.html +/// [`self`]: keyword.self.html +/// [`super`]: keyword.super.html +/// [Reference]: ../reference/items/use-declarations.html mod use_keyword {} #[doc(keyword = "where")] -- 2.44.0