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POPossibility to mix composite pattern and curiously recurring template pattern
 

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    <p>I have a composite pattern implementation, used for GUI components:</p> <pre><code>class CObject { private: CObject * m_pParent; CObjectContainer * m_pChildren; void private_foo() { this-&gt;foo(); //Calls private_foo for each child in container. m_pChildren-&gt;foo(); } public: virtual void foo() { //empty for base class } virtual CObject * duplicate() { //Do duplication code return new CObject(*this); } virtual CObject * detach() { //Remove this object (along with it's children) //from current tree. m_pParent-&gt;RemoveChild(this); m_pParent = nullptr; return this; } } class CSpecificObject : public CObject { public: virtual void foo() { //Specific code for this class } virtual CSpecificObject * duplicate() { //Overload, but the code only calls diferent constructor return new CSpecificObject(*this); } virtual CSpecificObject * detach() { //Note the code is identical. m_pParent-&gt;RemoveChild(this); m_pParent = nullptr; return this; } } </code></pre> <p>Unfortunately the number of inherited classes increases rapidly and the duplicate code (in given example only the detach() method) is giving me a headache.</p> <p>Is there a way to cleanly implement detach() methods, keeping the return type the same as the object, on which it is called?</p> <p>I was thinking about CRTP, but I can not think of a way to keep the dynamic polymorphism along with compile time polymorphism:</p> <pre><code>template &lt;Child&gt; class CObject { private: ... Child * detach() { m_pParent-&gt;RemoveChild(this); m_pParent = nullptr; return static_cast&lt;Child*&gt;(this); } ... } //Array of CObject* pointers is no longer possible. </code></pre>
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    1. USDave Schweisguth
    1. USVytis Valentinavičius
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