Macro try_opt::try_opt
[−]
[src]
macro_rules! try_opt { ($e:expr) => { ... }; }
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); }