macro_rules! ensure { ($predicate:expr, $context_selector:expr $(,)*) => { ... }; }
Expand description
Ensure a condition is true. If it is not, return from the function with an error.
use snafu::{ensure, Snafu};
#[derive(Debug, Snafu)]
enum Error {
InvalidUser { user_id: i32 },
}
fn example(user_id: i32) -> Result<(), Error> {
ensure!(user_id > 0, InvalidUser { user_id });
// After this point, we know that `user_id` is positive.
let user_id = user_id as u32;
Ok(())
}