auto_reset.h revision c7f5f8508d98d5952d42ed7648c2a8f30a4da156 
1// Copyright (c) 2009 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef BASE_AUTO_RESET_H_
6#define BASE_AUTO_RESET_H_
7
8#include "base/basictypes.h"
9
10// AutoReset is useful for setting a variable to some value only during a
11// particular scope.  If you have code that has to add "var = false;" or
12// "var = old_var;" at all the exit points of a block, for example, you would
13// benefit from using this instead.
14//
15// NOTE: Right now this is hardcoded to work on bools, since that covers all the
16// cases where we've used it.  It would be reasonable to turn it into a template
17// class in the future.
18
19class AutoReset {
20 public:
21  explicit AutoReset(bool* scoped_variable, bool new_value)
22      : scoped_variable_(scoped_variable),
23        original_value_(*scoped_variable) {
24    *scoped_variable_ = new_value;
25  }
26  ~AutoReset() { *scoped_variable_ = original_value_; }
27
28 private:
29  bool* scoped_variable_;
30  bool original_value_;
31
32  DISALLOW_COPY_AND_ASSIGN(AutoReset);
33};
34
35#endif  // BASE_AUTO_RESET_H_
36