#panic #breaktarget #nonlocal #setjmp #longjmp


Implementation of nonlocal breaks in Rust

1 unstable release

Uses old Rust 2015

0.1.0 Oct 31, 2016

#46 in #panic

31 downloads per month

MIT license

59 lines


Build Status

The breaktarget module defines one type: The BreakTarget type. A value of this type may be obtained by invoking BreakTarget::deploy.

BreakTarget::deploy takes a lambda, which is passed a reference to a BreakTarget. This object defines a single method, break_with, which takes a value of type T and returns control flow to the site of the BreakTarget::deploy call, producing the value as the result. If the lambda exits normally, it must also produce a value of type T, which is produced as the result of the BreakTarget::deploy call.

Important Notes

The nonlocal breaking is implemented using a panic to unwind the stack. Any open Mutexes which are closed by this unwinding will be poisoned, among with other unwinding specific effects.

If panic = "abort" is enabled, calls to break_with will abort the program


use breaktarget::Breaktarget;

let result = BreakTarget::deploy(|target| {
    // ... Some logic here
    // ... Some logic here
assert_eq!(result, 10i32);
use breaktarget::BreakTarget;

fn some_function(target: &BreakTarget<i32>, cond: bool) {
   if cond {

let result1 = BreakTarget::deploy(|target| {
    some_function(target, false);
assert_eq!(result1, 20);

let result2 = BreakTarget::deploy(|target| {
    some_function(target, true);
assert_eq!(result2, 10);

No runtime deps