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PORelational Operator Implementation Dilemma
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671760
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CommunityOwnedDate
CreationDate
2009-03-22T23:04:07.187
FavoriteCount
1
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2009-03-23T04:27:32.400
LastEditDate
2009-03-22T23:40:34.820
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4
ViewCount
478
LastEditorDisplayName
GSH110
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I'm in the process of designing several classes that need to support operators <code>!=</code>, <code>></code>, <code><=</code>, and <code>>=</code>. These operators will be implemented in terms of operators <code>==</code> and <code><</code>. At this stage, I need to make a choice between inheritance¹ and forcing my consumers to use <code>std::rel_ops</code>² "manually". [1] Inheritance (possible implementation): <pre><code>template<class T> class RelationalOperatorsImpl { protected: RelationalOperatorsImpl() {} ~RelationalOperatorsImpl() {} friend bool operator!=(const T& lhs, const T& rhs) {return !(lhs == rhs);} friend bool operator>(const T& lhs, const T& rhs) {return (rhs < lhs);} friend bool operator<=(const T& lhs, const T& rhs) {return !(rhs < lhs);} friend bool operator>=(const T& lhs, const T& rhs) {return !(lhs < rhs);} }; template<typename T> class Foo : RelationalOperatorsImpl< Foo<T> > { public: explicit Foo(const T& value) : m_Value(value) {} friend bool operator==(const Foo& lhs, const Foo& rhs) {return (lhs.m_Value == rhs.m_Value);} friend bool operator<(const Foo& lhs, const Foo& rhs) {return (lhs.m_Value < rhs.m_Value);} private: T m_Value; }; </code></pre> [2] <code>std::rel_ops</code> glue: <pre><code>template<typename T> class Foo { public: explicit Foo(const T& value) : m_Value(value) {} friend bool operator==(const Foo& lhs, const Foo& rhs) {return (lhs.m_Value == rhs.m_Value);} friend bool operator<(const Foo& lhs, const Foo& rhs) {return (lhs.m_Value < rhs.m_Value);} private: T m_Value; }; void Consumer() { using namespace std::rel_ops; //Operators !=, >, >=, and <= will be instantiated for Foo<T> (in this case) on demand. } </code></pre> I'm basically trying to avoid code repetition. Any thoughts as to which method "feels" better?
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Relational Operator Implementation Dilemma
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