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POHow do you overload templated function (specialized) in child class?
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  1. POHow do you overload templated function (specialized) in child class?
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    copied!<p>I have a base class with a templated function that has the general templated type, as well as specialized version. </p> <pre><code>#ifndef BASE_CLASS #define BASE_CLASS #include &lt;iostream&gt; using namespace std; struct Type1 { }; struct Type2 { }; class baseClass { public: template&lt;class Type&gt; void doStuff(Type &amp; t) { templateFunction(t); } template&lt;class Type&gt; void templateFunction(Type &amp; t); }; template&lt;class Type&gt; void baseClass::templateFunction(Type &amp; t) { cout &lt;&lt; "This is the generic function!" &lt;&lt; endl; } template&lt;&gt; void baseClass::templateFunction(Type1 &amp; t) { cout &lt;&lt; "This is the specialized function: - Type1" &lt;&lt; endl; } #endif </code></pre> <p>I also have a child class, that inherits from "baseClass". However, the child class requires different functionality for that specialization.</p> <pre><code>#ifndef CHILD_CLASS #define CHILD_CLASS #include "BaseClass.h" class ChildClass : public baseClass { public: }; template&lt;&gt; void ChildClass::templateFunction(Type1 &amp; t) { cout &lt;&lt; "We overloaded the specialized template function for type 1!" &lt;&lt; endl; } #endif </code></pre> <p>The above does not compile:</p> <p>ChildClass.h:13: error: no member function âtemplateFunctionâ declared in âChildClassâ ChildClass.h:13: error: invalid function declaration</p> <p>If I change the "overloaded" function to: </p> <pre><code>template&lt;&gt; void baseClass::templateFunction(Type1 &amp; t) { cout &lt;&lt; "We overloaded the specialized template function for type 1!" &lt;&lt; endl; } </code></pre> <p>I get: ChildClass.h:13: error: redefinition of âvoid baseClass::templateFunction(Type&amp;) [with Type = Type1]â BaseClass.h:36: error: âvoid baseClass::templateFunction(Type&amp;) [with Type = Type1]â previously declared here</p> <p><strong>How do I properly overload specialized template functions in child classes?</strong></p> <p>For reference, the main:</p> <pre><code>#include "BaseClass.h" #include "ChildClass.h" int main() { Type1 first; Type2 second; baseClass theBaseClass; ChildClass theChildClass; theBaseClass.doStuff(first); theBaseClass.doStuff(second); theChildClass.doStuff(first); theChildClass.doStuff(second); return 0; } </code></pre> <p>On the suggestion of: Kerrek SB, I've changed the ChildClass to:</p> <pre><code>#ifndef CHILD_CLASS #define CHILD_CLASS #include "BaseClass.h" class ChildClass : public baseClass { public: template&lt;class Type&gt; void templateFunction(Type &amp; t); }; template&lt;&gt; void ChildClass::templateFunction(Type1 &amp; t) { cout &lt;&lt; "We overloaded the specialized template function for type 1!" &lt;&lt; endl; } #endif </code></pre> <p>The output: </p> <pre><code>This is the specialized function: - Type1 This is the generic function! This is the specialized function: - Type1 This is the generic function! </code></pre> <p>I was hoping for:</p> <pre><code>This is the specialized function: - Type1 This is the generic function! We overloaded the specialized template function for type 1! This is the generic function! </code></pre> <p>So this still doesn't work.</p>
 

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