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    <p>This is a good reason to use boost::ptr_vector.</p> <p>It not only handles the fact that your objects need to be destroyed.<br> xtofl@: You forgot the virtual destructor.</p> <p>But it also makes the members look like objects by returning references rather than pointers. This allows you to use the standard algorithms much more naturally rather than playing around with pointers in your 'equal' function (which is very un C++ like).</p> <pre><code>#include &lt;boost/ptr_container/ptr_vector.hpp&gt; #include &lt;iostream&gt; class Shape { public: ~Shape() {} bool operator==(Shape const&amp; rhs) const { if (typeid(*this) != typeid(rhs)) { return false; } return this-&gt;isEqual(rhs); } private: virtual bool isEqual(Shape const&amp; rhs) const = 0; }; class Circle: public Shape { public: Circle(int r) :radius(r) {} private: virtual bool isEqual(Shape const&amp; r) const { Circle const&amp; rhs = dynamic_cast&lt;Circle const&amp;&gt;(r); return radius == rhs.radius; } int radius; }; class Rectangle: public Shape { public: Rectangle(int h,int w) :height(h) ,width(w) {} private: virtual bool isEqual(Shape const&amp; r) const { Rectangle const&amp; rhs = dynamic_cast&lt;Rectangle const&amp;&gt;(r); return (height == rhs.height) &amp;&amp; (width == rhs.width); } int height; int width; }; int main() { boost::ptr_vector&lt;Shape&gt; data; data.push_back(new Circle(5)); data.push_back(new Circle(6)); data.push_back(new Rectangle(7,4)); boost::ptr_vector&lt;Shape&gt;::iterator f; f = find(data.begin(),data.end(),Circle(6)); std::cout &lt;&lt; "Find(" &lt;&lt; (f - data.begin() ) &lt;&lt; ")" &lt;&lt; std::endl; } </code></pre>
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    1. USMartin York
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    1. COIt seems a little dangerous to rely on operator== to validate that the shapes are the same type before calling isEqual. I'd prefer to see that check inside isEqual itself, as xtofl did.
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      1. USMark Ransom
    2. COI prefer it in 'operator==' this way the code is not repeated. Why would you want it in isEqual? Note Shape is a pure virtual there can be no instances. I don't see why you think it is dangrorus?
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    3. COI have one doubt regarding checking typeids in base classes. Why this is actually needed ? Because call to correct isEqual function is resolved at runtime because of Polymorphism.
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