wrapping_macros

A macro for wrapping arithmetic.

Any code within a wrapping! { .. } block will be transformed as follows:

• a + b becomes a.wrapping_add(b). Similarly for - and *.
• a += b becomes a = a.wrapping_add(b). Similarly for -= and *=.
• -a becomes a.wrapping_mul(!0).

See this Internals thread for the motivation behind this crate.

Note: This crate uses internal compiler APIs, and so requires the Nightly version of Rust.

Cargo

Add this to your Cargo.toml:

toml wrapping_macros = "*"

Example

```rust

![feature(plugin)]

![plugin(wrapping_macros)]

fn main() { let mut sum = 0u8; for x in 0u8..50 { wrapping! { sum += x; } } } ```

Caveats

• This crate uses unstable APIs, and will only work on Rust Nightly.

• You cannot nest another macro invocation within a wrapping! block. For example, this will not work:

  rust let x = 41i32; wrapping! { println!("The answer is {}", x + 1); //~ ERROR }

  Instead, move the macro call out of the block:

  rust let x = 41i32; println!("The answer is {}", wrapping! { x + 1 });