Trait core::ops::Fn 1.0.0
[−]
[src]
#[lang = "fn"]pub trait Fn<Args>: FnMut<Args> { extern "rust-call" fn call(&self, args: Args) -> Self::Output; }
A version of the call operator that takes an immutable receiver.
Examples
Closures automatically implement this trait, which allows them to be
invoked. Note, however, that Fn
takes an immutable reference to any
captured variables. To take a mutable capture, implement FnMut
, and to
consume the capture, implement FnOnce
.
let square = |x| x * x; assert_eq!(square(5), 25);Run
Closures can also be passed to higher-level functions through a Fn
parameter (or a FnMut
or FnOnce
parameter, which are supertraits of
Fn
).
fn call_with_one<F>(func: F) -> usize where F: Fn(usize) -> usize { func(1) } let double = |x| x * 2; assert_eq!(call_with_one(double), 2);Run
Required Methods
extern "rust-call" fn call(&self, args: Args) -> Self::Output
This is called when the call operator is used.