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    <p>Ideally you have a static and perhaps a non-static <code>create()</code> functions. There is a clever way to accomplish this.</p> <ol> <li><p>Define a <code>SuperBase</code> class. It needs a virtual destructor and a pure virtual <code>create()</code> function. You'll use pointers/references to this class for normal late-binding OOP behaviours.</p></li> <li><p>Define a <code>Base</code> class template that inherits from <code>SuperBase</code>. <code>Base</code>'s template parameter will be the type of the <code>Derived</code> class. <code>Base</code> will also have a traits class template with a static function called <code>create()</code>. This static <code>create()</code> function will create a default object with <code>new</code>. Using the trait's <code>create()</code> function, <code>Base</code> will define both a <code>static_create()</code> and the pure virtual <code>SuperBase::create()</code> functions.</p></li> <li><p>Implement <code>Derived</code> by inheriting from <code>Base&lt;Derived&gt;</code>.</p></li> </ol> <p>One this is done, if you know you are using a derived type, then you can write <code>Derived::create()</code> to statically create a new one. If not, then you can always use an instance's <code>create()</code> method. Polymorphism is not broken since <code>SuperBase</code> would have the polymorphic interface you need/want --<code>Base&lt;D&gt;</code> is simply a helper class that auto defines the <code>static_create()</code> and <code>create()</code> functions so you would not normally use <code>Base&lt;D&gt;</code> directly.</p> <p>Sample code appears below:</p> <pre><code>#include &lt;memory&gt; #include &lt;iostream&gt; class SuperBase { public: virtual ~SuperBase() = default; virtual std::shared_ptr&lt;SuperBase&gt; create() const = 0; }; template &lt;typename T&gt; struct Base_Traits { static T* create() { return new T; } }; template &lt;typename Derived, typename Traits=Base_Traits&lt;Derived&gt;&gt; class Base : public SuperBase { public: // Define a static factory function... static std::shared_ptr&lt;SuperBase&gt; static_create() { return std::shared_ptr&lt;SuperBase&gt;{Traits::create()}; } // Define pure virtual implementation... std::shared_ptr&lt;SuperBase&gt; create() const override { return static_create(); } }; class Derived : public Base&lt;Derived&gt; { }; int main() { auto newone = Derived::static_create(); // Type known @ compile time auto anotherone = newone-&gt;create(); // Late binding; type not known @ compile time } </code></pre>
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    1. POIs it possible to make a non-virtual create method
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    1. USPaul Preney
    1. USPaul Preney
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      1. VTUpMod
    1. COThank you! I appreciate your approach!
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      1. USMartin Drozdik
 

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