rust-adorn

Python-style function decorators for Rust

Example usage:

```rust use adorn::{adorn, make_decorator};

[adorn(bar)]

fn foo(a: &mut u8, b: &mut u8, (c, _): (u8, u8)) { assert!(c == 4); *a = c; *b = c; }

fn bar(f: F, a: &mut u8, b: &mut u8, (c, d): (u8, u8)) where F: Fn(&mut u8, &mut u8, (u8, u8)) { assert!(c == 0 && d == 0); f(a, b, (4, 0)); *b = 100; }

fn main() { let mut x = 0; let mut y = 1; foo(&mut x, &mut y, (0, 0)); assert!(x == 4 && y == 100); } ```

In this case, foo will become:

rust fn foo(a: &mut u8, b: &mut u8, (c, d): (u8, u8)) { fn foo_inner(a: &mut u8, b: &mut u8, (c, _): (u8, u8)) { assert!(c == 4); *a = c; *b = c; } bar(foo_inner, a, b, (c, d)) }

In other words, calling foo() will actually call bar() wrapped around foo().

There is a #[make_decorator] attribute to act as sugar for creating decorators. For example,

```rust

[make_decorator(f)]

fn bar(a: &mut u8, b: &mut u8, (c, d): (u8, u8)) { assert!(c == 0 && d == 0); f(a, b, (4, 0)); // f was declared in the make_decorator annotation *b = 100; }

```

desugars to

rust fn bar<F>(f: F, a: &mut u8, b: &mut u8, (c, d): (u8, u8)) where F: Fn(&mut u8, &mut u8, (u8, u8)) { assert!(c == 0 && d == 0); f(a, b, (4, 0)); *b = 100; }

I intend to add support for decorating impl items and default trait methods too. Also passing arguments to the decorator; though rustc's current metaitem support limits us to strings (varargs are possible though).