Trait sp_runtime::traits::EnsureAddAssign

source · 
pub trait EnsureAddAssign: CheckedAdd + PartialOrd<Self> + Zero {
    fn ensure_add_assign(&mut self, v: Self) -> Result<(), ArithmeticError> { ... }
}
Expand description

Performs self addition that returns ArithmeticError instead of wrapping around on overflow.

Provided Methods§

Adds two numbers overwriting the left hand one, checking for overflow.

If it fails, ArithmeticError is returned.

Examples
use sp_arithmetic::traits::EnsureAddAssign;

let mut a: i32 = 10;
let b: i32 = 20;

a.ensure_add_assign(b).unwrap();
assert_eq!(a, 30);
use sp_arithmetic::{traits::EnsureAddAssign, ArithmeticError};

fn overflow() -> Result<(), ArithmeticError> {
    let mut max = u32::MAX;
    max.ensure_add_assign(1)?;
    Ok(())
}

fn underflow() -> Result<(), ArithmeticError> {
    let mut max = i32::MIN;
    max.ensure_add_assign(-1)?;
    Ok(())
}

assert_eq!(overflow(), Err(ArithmeticError::Overflow));
assert_eq!(underflow(), Err(ArithmeticError::Underflow));

Implementors§