scopeguard

Rust crate for a convenient RAII scope guard that will run a given closure when it goes out of scope, even if the code between panics (assuming unwinding panic).

The defer! macro and guard are no_std compatible (require only core), but the on unwinding / not on uwinding strategies requires linking to std.

Requires Rust 1.20.

Please read the API documentation here__

__ https://docs.rs/scopeguard/

|build_status|_ |crates|_

.. |build_status| image:: https://travis-ci.org/bluss/scopeguard.svg .. _build_status: https://travis-ci.org/bluss/scopeguard

.. |crates| image:: http://meritbadge.herokuapp.com/scopeguard .. _crates: https://crates.io/crates/scopeguard

How to use

.. code:: rust

#[macro_use(defer)] extern crate scopeguard;

use scopeguard::guard;

fn f() {
    defer!(println!("Called at return or panic"));
    panic!();
}

use std::fs::File;
use std::io::Write;

fn g() {
    let f = File::create("newfile.txt").unwrap();
    let mut file = guard(f, |f| {
        // write file at return or panic
        let _ = f.sync_all();
    });
    // Access the file through the scope guard itself
    file.write_all(b"test me\n").unwrap();
}

Recent Changes

• 1.0.0

  • Change the closure type from FnMut(&mut T) to FnOnce(T): Passing the inner value by value instead of a mutable reference is a breaking change, but allows the guard closure to consume it. (by @tormol)

  • Add defer_on_success!{}, guard_on_success() and OnSuccess strategy, which triggers when scope is exited without panic. It's the opposite to OnUnwind / guard_on_unwind() / defer_on_unwind!{}.

  • Add ScopeGuard::into_inner(), which "defuses" the guard and returns the guarded value. (by @tormol)

  • Implement Sync for guards with non-Sync closures.

  • Require Rust 1.20

• 0.3.3

  • Use #[inline] on a few more functions by @stjepang (#14)
  • Add examples to crate documentation

• 0.3.2

  • Add crate categories

• 0.3.1

  • Add defer_on_unwind!, Strategy trait
  • Rename Guard → ScopeGuard
  • Add ScopeGuard::with_strategy.
  • ScopeGuard now implements Debug.
  • Require Rust 1.11

• 0.2.0

  • Require Rust 1.6
  • Use no_std unconditionally
  • No other changes

• 0.1.2

  • Add macro defer!()