StackOverflow2013

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PO
primarykey
Id
11802080
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
1
CommunityOwnedDate
CreationDate
2012-08-03T19:27:34.337
FavoriteCount
0
LastActivityDate
2012-08-04T02:35:06.210
LastEditDate
2012-08-04T02:35:06.210
LastEditorUserId
484307
OwnerUserId
484307
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11796121
PostTypeId
2
Score
21
ViewCount
0
LastEditorDisplayName
text
Body
This can be done in C++11 using variadic templates. Continuing from Pete's answer: <pre><code>// Visitor template declaration template<typename... Types> class Visitor; // specialization for single type template<typename T> class Visitor<T> { public: virtual void visit(T & visitable) = 0; }; // specialization for multiple types template<typename T, typename... Types> class Visitor<T, Types...> : public Visitor<Types...> { public: // promote the function(s) from the base class using Visitor<Types...>::visit; virtual void visit(T & visitable) = 0; }; template<typename... Types> class Visitable { public: virtual void accept(Visitor<Types...>& visitor) = 0; }; template<typename Derived, typename... Types> class VisitableImpl : public Visitable<Types...> { public: virtual void accept(Visitor<Types...>& visitor) { visitor.visit(static_cast<Derived&>(*this)); } }; </code></pre> Subclasses of <code>Visitable</code>: <pre><code>class Mesh : public Object, public VisitableImpl<Mesh, Mesh, Text> {}; class Text : public Object, public VisitableImpl<Text, Mesh, Text> {}; </code></pre> A <code>Visitor</code> subclass: <pre><code>class Renderer : public Visitor<Mesh, Text> {}; </code></pre> It's not clear what the <code>value_type</code> of your <code>Scene</code> container is but you need to obtain a reference or pointer to <code>Visitable<Mesh, Text></code> on which to call <code>accept</code>: <pre><code>for(Scene::iterator it = scene.begin(); it != scene.end(); ++it) { Visitable<Mesh, Text>& object = static_cast<Visitable<Mesh, Text>&>(*it); if(pre_visit(object)) { object.accept(*this); post_visit(object); } } </code></pre>
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1. This table or related slice is empty.
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1. POImplementing the visitor pattern using C++ Templates
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 PTQuestion
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1. PTAnswer
UserLastEditorUserId
1. USAndrew Durward
UserOwnerUserId
1. USAndrew Durward
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1. POImplementing the visitor pattern using C++ Templates
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