1 files changed, 97 insertions, 0 deletions
diff --git a/src/libcore/unstable/finally.rs b/src/libcore/unstable/finally.rs
new file mode 100644
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+++ b/src/libcore/unstable/finally.rs
@@ -0,0 +1,97 @@
+// 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
+
+~~~
+do || {
+    ...
+}.finally {
+    alway_run_this();
+}
+~~~
+*/
+
+use ops::Drop;
+use task::{spawn, failing};
+
+pub trait Finally<T> {
+    fn finally(&self, dtor: &fn()) -> T;
+}
+
+impl<T> Finally<T> for &fn() -> T {
+    fn finally(&self, dtor: &fn()) -> T {
+        let _d = Finallyalizer {
+            dtor: dtor
+        };
+
+        (*self)()
+    }
+}
+
+struct Finallyalizer {
+    dtor: &fn()
+}
+
+impl Drop for Finallyalizer {
+    fn finalize(&self) {
+        (self.dtor)();
+    }
+}
+
+#[test]
+fn test_success() {
+    let mut i = 0;
+    do (|| {
+        i = 10;
+    }).finally {
+        assert !failing();
+        assert i == 10;
+        i = 20;
+    }
+    assert i == 20;
+}
+
+#[test]
+#[ignore(cfg(windows))]
+#[should_fail]
+fn test_fail() {
+    let mut i = 0;
+    do (|| {
+        i = 10;
+        fail!();
+    }).finally {
+        assert failing();
+        assert i == 10;
+    }
+}
+
+#[test]
+fn test_retval() {
+    let i = do (fn&() -> int {
+        10
+    }).finally { };
+    assert i == 10;
+}
+
+#[test]
+fn test_compact() {
+    // FIXME #4727: Should be able to use a fn item instead
+    // of a closure for do_some_fallible_work,
+    // but it's a type error.
+    let do_some_fallible_work: &fn() = || { };
+    fn but_always_run_this_function() { }
+    do_some_fallible_work.finally(
+        but_always_run_this_function);
+}