DropGuard in core::mem

DropGuard in core::mem - Rust

pub struct DropGuard<T, F>where
    F: FnOnce(T),
{ /* private fields */ }

🔬This is a nightly-only experimental API. (drop_guard #144426)

Expand description

Wrap a value and run a closure when dropped.

This is useful for quickly creating destructors inline.

§Examples

#![feature(drop_guard)]

use std::mem::DropGuard;

{
    // Create a new guard around a string that will
    // print its value when dropped.
    let s = String::from("Chashu likes tuna");
    let mut s = DropGuard::new(s, |s| println!("{s}"));

    // Modify the string contained in the guard.
    s.push_str("!!!");

    // The guard will be dropped here, printing:
    // "Chashu likes tuna!!!"
}

Source §

Source

🔬This is a nightly-only experimental API. (drop_guard #144426)

Create a new instance of DropGuard.

§Example

#![feature(drop_guard)]

use std::mem::DropGuard;

let value = String::from("Chashu likes tuna");
let guard = DropGuard::new(value, |s| println!("{s}"));

Source

🔬This is a nightly-only experimental API. (drop_guard #144426)

Consumes the DropGuard, returning the wrapped value.

This will not execute the closure. It is typically preferred to call this function instead of mem::forget because it will return the stored value and drop variables captured by the closure instead of leaking their owned resources.

§Example

#![feature(drop_guard)]

use std::mem::DropGuard;

let value = String::from("Nori likes chicken");
let guard = DropGuard::new(value, |s| println!("{s}"));
assert_eq!(guard.dismiss(), "Nori likes chicken");