Trait Fallible

Source

pub trait Fallible {
    type Error;
}

Expand description

A type with fallible operations that return its associated error type.

Fallible turns an error type parameter into an associated type of another parameter. You can equip an existing type with a Fallible implementation by wrapping it in a Strategy.

§Example

use rancor::{Failure, Fallible, Strategy};

trait Operator<E = <Self as Fallible>::Error> {
    fn operate(&self, lhs: i32, rhs: i32) -> Result<i32, E>;
}

impl<T: Operator<E> + ?Sized, E> Operator<E> for Strategy<T, E> {
    fn operate(&self, lhs: i32, rhs: i32) -> Result<i32, E> {
        T::operate(self, lhs, rhs)
    }
}

struct Add;

impl<E> Operator<E> for Add {
    fn operate(&self, lhs: i32, rhs: i32) -> Result<i32, E> {
        Ok(lhs + rhs)
    }
}

fn operate_one_one<T: Operator + Fallible>(
    operator: &T,
) -> Result<i32, T::Error> {
    operator.operate(1, 1)
}

assert_eq!(
    operate_one_one(Strategy::<_, Failure>::wrap(&mut Add)),
    Ok(2)
);