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// Copyright 2013 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
The Finally trait provides a method, `finally` on
stack closures that emulates Java-style try/finally blocks.
# Example
```
(|| {
...
}).finally(|| {
always_run_this();
})
```
*/
use ops::Drop;
#[cfg(test)] use task::failing;
pub trait Finally<T> {
fn finally(&self, dtor: ||) -> T;
}
macro_rules! finally_fn {
($fnty:ty) => {
impl<T> Finally<T> for $fnty {
fn finally(&self, dtor: ||) -> T {
let _d = Finallyalizer {
dtor: dtor
};
(*self)()
}
}
}
}
impl<'a,T> Finally<T> for 'a || -> T {
fn finally(&self, dtor: ||) -> T {
let _d = Finallyalizer {
dtor: dtor
};
(*self)()
}
}
finally_fn!(extern "Rust" fn() -> T)
struct Finallyalizer<'a> {
dtor: 'a ||
}
#[unsafe_destructor]
impl<'a> Drop for Finallyalizer<'a> {
#[inline]
fn drop(&mut self) {
(self.dtor)();
}
}
#[test]
fn test_success() {
let mut i = 0;
(|| {
i = 10;
}).finally(|| {
assert!(!failing());
assert_eq!(i, 10);
i = 20;
});
assert_eq!(i, 20);
}
#[test]
#[should_fail]
fn test_fail() {
let mut i = 0;
(|| {
i = 10;
fail!();
}).finally(|| {
assert!(failing());
assert_eq!(i, 10);
})
}
#[test]
fn test_retval() {
let closure: || -> int = || 10;
let i = closure.finally(|| { });
assert_eq!(i, 10);
}
#[test]
fn test_compact() {
fn do_some_fallible_work() {}
fn but_always_run_this_function() { }
do_some_fallible_work.finally(
but_always_run_this_function);
}
|
