3 unstable releases
Uses old Rust 2015
0.2.0 | Jan 22, 2019 |
---|---|
0.1.1 | Jul 5, 2015 |
0.1.0 | Jul 5, 2015 |
#34 in #early
89 downloads per month
Used in 8 crates
(5 directly)
4KB
Deprecated
Rust now allows the ?
operator to be used on Option
. The try_opt!
example further below
can be rewritten as the following:
use std::collections::HashMap;
fn map_add_checked(map: &HashMap<&str, i32>, lhs: &str, rhs: &str) -> Option<i32> {
let lhs = map.get(lhs)?;
let rhs = map.get(rhs)?;
lhs.checked_add(*rhs)
}
fn main() {
let mut map = HashMap::new();
map.insert("foo", 2);
map.insert("bar", 4);
map.insert("baz", 12);
assert_eq!(map_add_checked(&map, "foo", "bar"), Some(6));
assert_eq!(map_add_checked(&map, "baz", "qux"), None);
}
Helper macro for unwrapping Option
values while returning early with an
error if the value of the expression is None
. Can only be used in
functions that return Option
because of the early return of None
that
it provides.
Examples
#[macro_use]
extern crate try_opt;
use std::collections::HashMap;
fn map_add_checked(map: &HashMap<&str, i32>, lhs: &str, rhs: &str) -> Option<i32> {
let lhs = try_opt!(map.get(lhs));
let rhs = try_opt!(map.get(rhs));
lhs.checked_add(*rhs)
}
fn main() {
let mut map = HashMap::new();
map.insert("foo", 2);
map.insert("bar", 4);
map.insert("baz", 12);
assert_eq!(map_add_checked(&map, "foo", "bar"), Some(6));
assert_eq!(map_add_checked(&map, "baz", "qux"), None);
}