Function elim_failure

pub fn elim_failure()

消除失败

1. 类型系统保证函数契约

fn sum(a: i32, b: i32) -> i32 {
    a + b
}
fn main() {
    sum(1u32, 2u32); // 违反契约，报错
}

2. 断言用于防御

fn extend_vec(v: &mut Vec<i32>, i: i32) {
    assert!(v.len() == 5);
    v.push(i);
}
fn main() {
    let mut vec = vec![1, 2, 3];
    extend_vec(&mut vec, 4);
    extend_vec(&mut vec, 5);
    extend_vec(&mut vec, 6); // panic!
}