1 // Copyright (c) 2010 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 #pragma once 8 9 #include "base/basictypes.h" 10 11 // AutoResetValue is useful for setting a variable to some value only 12 // during a particular scope. If you have code that has to add "var = 13 // false;" or "var = old_var;" at all the exit points of a block, for 14 // example, you would benefit from using this instead. 15 // 16 // This should be obvious, but note that the AutoResetValue instance 17 // should have a shorter lifetime than the scoped_variable, to prevent 18 // writing to invalid memory when the AutoResetValue goes out of 19 // scope. 20 21 template<typename T> 22 class AutoReset { 23 public: AutoReset(T * scoped_variable,T new_value)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 ~AutoReset()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 #endif // BASE_AUTO_RESET_H_ 40