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copied!<p>For your request to do </p> <pre><code>if (InSet(value)(GetValue1(), GetValue2(), GetValue3())) { // Do something here... } </code></pre> <p>Try this:</p> <pre><code>template <typename T> class InSetHelper { const T &Value; void operator=(const InSetHelper &); public: InSetHelper(const T &value) : Value(value) {} template<class Other, class Another> bool operator()(const Other &value1, const Another &value2) const { return Value == value1 || Value == value2; } template<class Other, class Another, class AThird> bool operator()(const Other &value1, const Another &value2, const AThird &value3) const { return Value == value1 || Value == value2 || Value == value3; } }; template <typename T> InSetHelper<T> InSet(const T &value) { return InSetHelper<T>(value); } </code></pre> <p>This syntax might be more clear though:</p> <pre><code>if (MakeSet(GetValue1(), GetValue2(), GetValue3()).Contains(value)) { // Do something here... } template <typename T, typename U, typename V> class Set3 { const T& V1; const U& V2; const V& V3; void operator=(const Set3 &); public: Set3(const T &v1, const U &v2, const V &v3) : V1(v1), V2(v2), V3(v3) {} template <typename W> bool Contains(const W &v) const { return V1 == v || V2 == v || V3 == v; } }; template <typename T, typename U> class Set2 { // as above }; template <typename T, typename U, typename V> Set3<T, U, V> MakeSet(const T &v1, const U &v2, const V &v3) { return Set3<T, U, V>(v1, v2, v3); } template <typename T, typename U> Set3<T, U> MakeSet(const T &v1, const U &v23) { return Set3<T, U, V>(v1, v2); } </code></pre> <p>If those values are really part of a tree or a linked list, then you have your set/container already, and your best bet is to just use some recursion:</p> <pre><code>parent.ThisOrDescendantHasValue(value); </code></pre> <p>You'd just add this to whatever class parent and child belong to:</p> <pre><code>class Node { public: Value GetValue(); Node *GetChild(); bool ThisOrDescendantHasValue(const Value &value) { return GetValue() == value || (GetChild() && GetChild->ThisOrDescendantHasValue(value)); } }; </code></pre>

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