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| 1 // Copyright (c) 2011 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 // base::AutoReset<> is useful for setting a variable to a new value only within | |
| 11 // a particular scope. An base::AutoReset<> object resets a variable to its | |
| 12 // original value upon destruction, making it an alternative to writing | |
| 13 // "var = false;" or "var = old_val;" at all of a block's exit points. | |
| 14 // | |
| 15 // This should be obvious, but note that an base::AutoReset<> instance should | |
| 16 // have a shorter lifetime than its scoped_variable, to prevent invalid memory | |
| 17 // writes when the base::AutoReset<> object is destroyed. | |
| 18 | |
| 19 namespace base { | |
| 20 | |
| 21 template<typename T> | |
| 22 class AutoReset { | |
| 23 public: | |
| 24 AutoReset(T* scoped_variable, T new_value) | |
| 25 : scoped_variable_(scoped_variable), | |
| 26 original_value_(*scoped_variable) { | |
| 27 *scoped_variable_ = new_value; | |
| 28 } | |
| 29 | |
| 30 ~AutoReset() { *scoped_variable_ = original_value_; } | |
| 31 | |
| 32 private: | |
| 33 T* scoped_variable_; | |
| 34 T original_value_; | |
| 35 | |
| 36 DISALLOW_COPY_AND_ASSIGN(AutoReset); | |
| 37 }; | |
| 38 | |
| 39 } // namespace base | |
| 40 | |
| 41 #endif // BASE_AUTO_RESET_H_ | |
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