diff options
| -rw-r--r-- | src/libcore/fmt/mod.rs | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/libcore/fmt/mod.rs b/src/libcore/fmt/mod.rs index da873f76d1b..ee1cab4076d 100644 --- a/src/libcore/fmt/mod.rs +++ b/src/libcore/fmt/mod.rs @@ -269,6 +269,50 @@ impl<'a> Display for Arguments<'a> { /// Format trait for the `:?` format. Useful for debugging, all types /// should implement this. +/// +/// Generally speaking, you should just `derive` a `Debug` implementation. +/// +/// # Examples +/// +/// Deriving an implementation: +/// +/// ``` +/// #[derive(Debug)] +/// struct Point { +/// x: i32, +/// y: i32, +/// } +/// +/// let origin = Point { x: 0, y: 0 }; +/// +/// println!("The origin is: {:?}", origin); +/// ``` +/// +/// Manually implementing: +/// +/// ``` +/// use std::fmt; +/// +/// struct Point { +/// x: i32, +/// y: i32, +/// } +/// +/// impl fmt::Debug for Point { +/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result { +/// write!(f, "({}, {})", self.x, self.y) +/// } +/// } +/// +/// let origin = Point { x: 0, y: 0 }; +/// +/// println!("The origin is: {:?}", origin); +/// ``` +/// +/// There are a number of `debug_*` methods on `Formatter` to help you with manual +/// implementations, such as [`debug_struct`][debug_struct]. +/// +/// [debug_struct]: ../std/fmt/struct.Formatter.html#method.debug_struct #[stable(feature = "rust1", since = "1.0.0")] #[rustc_on_unimplemented = "`{Self}` cannot be formatted using `:?`; if it is \ defined in your crate, add `#[derive(Debug)]` or \ |