| % Conditional Compilation |
| |
| <small>There is a new edition of the book and this is an old link.</small> |
| |
| > Sometimes one wants to have different compiler outputs from the same code, depending on build target, such as targeted operating system, or to enable release builds. |
| > Configuration options are either provided by the compiler or passed in on the command line using. |
| > Rust code then checks for their presence using the `#[cfg(...)]` attribute |
| |
| ```rust |
| // The function is only included in the build when compiling for macOS |
| #[cfg(target_os = "macos")] |
| fn macos_only() { |
| // ... |
| } |
| ``` |
| |
| --- |
| |
| This particular chapter does not exist in [the second edition][2]. |
| The best place to learn about it is [the Rust Reference][3]. |
| |
| * **[In the Rust Reference: Ch 5 — Conditional Compilation][3]** |
| * <small>[In the first edition: Ch 4.3 — Conditional Compilation][1]</small> |
| |
| |
| [1]: https://doc.rust-lang.org/1.30.0/book/first-edition/conditional-compilation.html |
| [2]: index.html |
| [3]: ../reference/conditional-compilation.html |
