Understanding C++ Expression Templates - Angelika Langer

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38Policy Specifications! classic quick sort function from C library– uses function pointer for sorting criterionvoid qsort( void *base, size_t num, size_t width,int (*compare )(const void *elem1, const void *elem2 ));! sort algorithm from the C++ library– uses comparitor type (function pointer or function object)templatevoid sort(RandomAccessIteratorfirst,RandomAccessIterator last,Comparator cmp);© Copyright 1995-2000 by Angelika Langer. All Rights Reserved.http://www.AngelikaLanger.com(75)last update: 11/7/2005 ,21:37The Strategy PatternThe Strategy pattern (also known as Policy) provides a way toconfigure a class or function (the context) with one of manybehaviors (the strategies).! There is a family of strategies that have a certain interfacein common.! The context uses this interface for implementing itsoperations.Examples:– allocation strategies of a container– sorting order used by a sort algorithm or a sorted collection– synchronization policy of objects© Copyright 1995-2000 by Angelika Langer. All Rights Reserved.http://www.AngelikaLanger.com(77)last update: 11/7/2005 ,21:37
39The Strategy PatternContextStrategy* sContextInterface()StrategyStrategyInterface()s->StrategyInterface()ConcreteStrategyStrategyInterface()ConcreteStrategyStrategyInterface()© Copyright 1995-2000 by Angelika Langer. All Rights Reserved.http://www.AngelikaLanger.com(78)last update: 11/7/2005 ,21:37An Example - Sorting of StringsContext:– a class or function that sorts strings, or– a sorted collectionStrategy:– ASCII sorting order– case-insensitive sorting order– culture-sensitive, dictionary sorting order© Copyright 1995-2000 by Angelika Langer. All Rights Reserved.http://www.AngelikaLanger.com(79)last update: 11/7/2005 ,21:37
Page 1 and 2: 1Understanding C++Expression Templa
Page 3 and 4: 3Runtime Computation of FactorialTh
Page 5 and 6: 5The RecursionRecursive definition
Page 7 and 8: 7Goal! efficient computation of ari
Page 9 and 10: 9Agenda! compile-time computation o
Page 11 and 12: 11A Typical Composite StructureaCom
Page 13 and 14: 13The ComponentThe base class that
Page 15 and 16: 15A Simplified OO ImplementationEli
Page 17: 17Implementation Using TemplatesDot
Page 20 and 21: 20The Interpreter PatternThe Interp
Page 22 and 23: 22OO Implementation à la GOFAbstra
Page 24 and 25: 24The ClientThe code that creates t
Page 26 and 27: 26The Non-Terminal Expressionstempl
Page 28 and 29: 28First attemptDefine the creator f
Page 30 and 31: 30Fine TuningDefine a helper functi
Page 33 and 34: 33Incorporating FunctionsWe can inc
Page 35 and 36: 35Run-Time PolymorphismClassic obje
Page 37: 37Run-Time vs. Compile-Time Dispatc
Page 41 and 42: 41The Strategiesclass Comparator {p
Page 43 and 44: 43The Strategiesclass Ascii {public
Page 45 and 46: 45Examples from Standard C++! sorti
Page 47 and 48: 47Alexandrescu’s Smart Pointer! t
Page 49 and 50: 49Expression Template LibrariesRefe
Page 51: 51Contact InfoAngelika LangerTraini

Understanding C++ Expression Templates - Angelika Langer

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