rgo - Rust Scope Guard Implementation

A scope guard will run a given closure when it goes out of scope, even if the code between panics (as long as panic doesn't abort).

Installation

Add this to your Cargo.toml:

[dependencies]
rgo = "0.2.0"

Usage

Basic Example

extern crate rgo;

fn f() {
    let _guard = rgo::guard((), |_| {
        println!("Hello Scope Exit!");
    });

    // rest of the code here

    // Here, at the end of `_guard`'s scope, the guard's closure is called
    // It is also called if we exit this scope through unwinding instead
}

defer! Macro

#[macro_use(defer)] extern crate rgo;

use std::cell::Cell;

fn main() {
    let drop_counter = Cell::new(0);
    {
        defer! {
            drop_counter.set(1 + drop_counter.get());
        }

        // Do regular operations here
        assert_eq!(drop_counter.get(), 0);
    }
    assert_eq!(drop_counter.get(), 1);
}

Scope Guard with Value

extern crate rgo;

use std::fs::File;
use std::io::{self, Write};

fn try_main() -> io::Result<()> {
    let f = File::create("newfile.txt")?;
    let mut file = rgo::guard(f, |f| {
        // ensure we flush file at return or panic
        let _ = f.sync_all();
    });
    file.write_all(b"test me\n").map(|_| ())
}

Crate Features

• use_std (enabled by default): Enables the OnUnwind and OnSuccess strategies
• Disable use_std to use no_std

Rust Version

This crate requires Rust 1.20 or later.