macro_rules! unwrap_or_else {
($e:expr, || $v:expr $(,)?) => { ... };
($opt:expr, | $($anything:tt)* ) => { ... };
($e:expr, $v:expr $(,)?) => { ... };
}
Expand description
A const equivalent of Option::unwrap_or_else
§Example
use konst::option;
const ARR: &[u32] = &[
// You can use a closure-like syntax to run code when the Option argument is None.
// `return` inside the "closure" returns from the function where this macro is called.
option::unwrap_or_else!(Some(3), || loop{}),
option::unwrap_or_else!(None, || 5),
// You can also pass functions
option::unwrap_or_else!(Some(8), thirteen),
option::unwrap_or_else!(None, thirteen),
];
assert_eq!(ARR, &[3, 5, 8, 13]);
const fn thirteen() -> u32 {
13
}