Crate extend

Create extensions for types you don't own with extension traits but without the boilerplate.

Example:

use extend::ext;

#[ext]
impl<T: Ord> Vec<T> {
    fn sorted(mut self) -> Self {
        self.sort();
        self
    }
}

fn main() {
    assert_eq!(
        vec![1, 2, 3],
        vec![2, 3, 1].sorted(),
    );
}

How does it work?

Under the hood it generates a trait with methods in your impl and implements those for the type you specify. The code shown above expands roughly to:

trait VecExt<T: Ord> {
    fn sorted(self) -> Self;
}

impl<T: Ord> VecExt<T> for Vec<T> {
    fn sorted(mut self) -> Self {
        self.sort();
        self
    }
}

Configuration

You can configure:

• The visibility of the trait. The default visibility is private. Example: #[ext(pub)]. This must be the first argument to the attribute
• The name of the generated extension trait. Example: #[ext(name = MyExt)].
• Whether or not the generated trait should be sealed. Example: #[ext(sealed = false)]. The default is true.
• Which supertraits the generated extension trait should have. Default is no supertraits. Example: #[ext(supertraits = Default + Clone)].

More examples:

use extend::ext;

#[ext(name = SortedVecExt)]
impl<T: Ord> Vec<T> {
    fn sorted(mut self) -> Self {
        self.sort();
        self
    }
}

#[ext(pub(crate))]
impl i32 {
    fn double(self) -> i32 {
        self * 2
    }
}

#[ext(pub, name = ResultSafeUnwrapExt)]
impl<T> Result<T, std::convert::Infallible> {
    fn safe_unwrap(self) -> T {
        match self {
            Ok(t) => t,
            Err(_) => unreachable!(),
        }
    }
}

#[ext(supertraits = Default + Clone)]
impl String {
    fn my_length(self) -> usize {
        self.len()
    }
}

Attribute Macros

ext	See crate docs for more info.