| // Copyright (c) 2011 The Chromium Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style license that can be |
| // found in the LICENSE file. |
| |
| #ifndef BASE_AUTO_RESET_H_ |
| #define BASE_AUTO_RESET_H_ |
| #pragma once |
| |
| #include "base/basictypes.h" |
| |
| // AutoReset<> is useful for setting a variable to a new value only within a |
| // particular scope. An AutoReset<> object resets a variable to its original |
| // value upon destruction, making it an alternative to writing "var = false;" |
| // or "var = old_val;" at all of a block's exit points. |
| // |
| // This should be obvious, but note that an AutoReset<> instance should have a |
| // shorter lifetime than its scoped_variable, to prevent invalid memory writes |
| // when the AutoReset<> object is destroyed. |
| |
| template<typename T> |
| class AutoReset { |
| public: |
| AutoReset(T* scoped_variable, T new_value) |
| : scoped_variable_(scoped_variable), |
| original_value_(*scoped_variable) { |
| *scoped_variable_ = new_value; |
| } |
| |
| ~AutoReset() { *scoped_variable_ = original_value_; } |
| |
| private: |
| T* scoped_variable_; |
| T original_value_; |
| |
| DISALLOW_COPY_AND_ASSIGN(AutoReset); |
| }; |
| |
| #endif // BASE_AUTO_RESET_H_ |