[−][src]Function boolean_enums::lstd::convert::identity
pub const fn identity<T>(x: T) -> T
🔬 This is a nightly-only experimental API. (
convert_id
)An identity function.
Two things are important to note about this function:
-
It is not always equivalent to a closure like
|x| x
since the closure may coercex
into a different type. -
It moves the input
x
passed to the function.
While it might seem strange to have a function that just returns back the input, there are some interesting uses.
Examples
Using identity
to do nothing among other interesting functions:
#![feature(convert_id)] use std::convert::identity; fn manipulation(x: u32) -> u32 { // Let's assume that this function does something interesting. x + 1 } let _arr = &[identity, manipulation];
Using identity
to get a function that changes nothing in a conditional:
#![feature(convert_id)] use std::convert::identity; let do_stuff = if condition { manipulation } else { identity }; // do more interesting stuff.. let _results = do_stuff(42);
Using identity
to keep the Some
variants of an iterator of Option<T>
:
#![feature(convert_id)] use std::convert::identity; let iter = vec![Some(1), None, Some(3)].into_iter(); let filtered = iter.filter_map(identity).collect::<Vec<_>>(); assert_eq!(vec![1, 3], filtered);