nordic-dev.net/rust
nordic-dev.net/rust
2
0
Fork 0
mirror of https://github.com/rust-lang/rust.git synced 2025-02-14 16:03:17 +00:00
Code Issues Packages Projects Releases Wiki Activity

Move all Default docs from module to trait

Browse Source 
I had already copied the implementation example in a previous commit;
this copies the explanation and usage examples to the general trait
description.
This commit is contained in:
Carol (Nichols || Goulding) 2016-05-23 13:47:28 -04:00
parent d81a999b54
commit 1b32298396
1 changed files with 42 additions and 73 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

115
src/libcore/default.rs
View File

@ -9,76 +9,6 @@
// except according to those terms.
//! The `Default` trait for types which may have meaningful default values.
//!
//! Sometimes, you want to fall back to some kind of default value, and
//! don't particularly care what it is. This comes up often with `struct`s
//! that define a set of options:
//!
//! ```
//! # #[allow(dead_code)]
//! struct SomeOptions {
//! foo: i32,
//! bar: f32,
//! }
//! ```
//!
//! How can we define some default values? You can use `Default`:
//!
//! ```
//! # #[allow(dead_code)]
//! #[derive(Default)]
//! struct SomeOptions {
//! foo: i32,
//! bar: f32,
//! }
//!
//!
//! fn main() {
//! let options: SomeOptions = Default::default();
//! }
//! ```
//!
//! Now, you get all of the default values. Rust implements `Default` for various primitives types.
//! If you have your own type, you need to implement `Default` yourself:
//!
//! ```
//! # #![allow(dead_code)]
//! enum Kind {
//! A,
//! B,
//! C,
//! }
//!
//! impl Default for Kind {
//! fn default() -> Kind { Kind::A }
//! }
//!
//! #[derive(Default)]
//! struct SomeOptions {
//! foo: i32,
//! bar: f32,
//! baz: Kind,
//! }
//!
//!
//! fn main() {
//! let options: SomeOptions = Default::default();
//! }
//! ```
//!
//! If you want to override a particular option, but still retain the other defaults:
//!
//! ```
//! # #[allow(dead_code)]
//! # #[derive(Default)]
//! # struct SomeOptions {
//! # foo: i32,
//! # bar: f32,
//! # }
//! fn main() {
//! let options = SomeOptions { foo: 42, ..Default::default() };
//! }
//! ```
#![stable(feature = "rust1", since = "1.0.0")]
@ -86,10 +16,49 @@ use marker::Sized;
/// A trait for giving a type a useful default value.
///
/// For more information, see
/// [the module-level documentation][module].
/// Sometimes, you want to fall back to some kind of default value, and
/// don't particularly care what it is. This comes up often with `struct`s
/// that define a set of options:
///
/// [module]: ../../std/default/index.html
/// ```
/// # #[allow(dead_code)]
/// struct SomeOptions {
/// foo: i32,
/// bar: f32,
/// }
/// ```
///
/// How can we define some default values? You can use `Default`:
///
/// ```
/// # #[allow(dead_code)]
/// #[derive(Default)]
/// struct SomeOptions {
/// foo: i32,
/// bar: f32,
/// }
///
///
/// fn main() {
/// let options: SomeOptions = Default::default();
/// }
/// ```
///
/// Now, you get all of the default values. Rust implements `Default` for various primitives types.
///
/// If you want to override a particular option, but still retain the other defaults:
///
/// ```
/// # #[allow(dead_code)]
/// # #[derive(Default)]
/// # struct SomeOptions {
/// # foo: i32,
/// # bar: f32,
/// # }
/// fn main() {
/// let options = SomeOptions { foo: 42, ..Default::default() };
/// }
/// ```
///
/// ## Derivable
///