| # Attributes |
| |
| An attribute is metadata applied to some module, crate or item. This metadata |
| can be used to/for: |
| |
| <!-- TODO: Link these to their respective examples --> |
| |
| * [conditional compilation of code][cfg] |
| * [set crate name, version and type (binary or library)][crate] |
| * disable [lints][lint] (warnings) |
| * enable compiler features (macros, glob imports, etc.) |
| * link to a foreign library |
| * mark functions as unit tests |
| * mark functions that will be part of a benchmark |
| |
| When attributes apply to a whole crate, their syntax is `#![crate_attribute]`, |
| and when they apply to a module or item, the syntax is `#[item_attribute]` |
| (notice the missing bang `!`). |
| |
| Attributes can take arguments with different syntaxes: |
| |
| * `#[attribute = "value"]` |
| * `#[attribute(key = "value")]` |
| * `#[attribute(value)]` |
| |
| Attributes can have multiple values and can be separated over multiple lines, too: |
| |
| ```rust,ignore |
| #[attribute(value, value2)] |
| |
| |
| #[attribute(value, value2, value3, |
| value4, value5)] |
| ``` |
| |
| [cfg]: attribute/cfg.md |
| [crate]: attribute/crate.md |
| [lint]: https://en.wikipedia.org/wiki/Lint_%28software%29 |
