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POrequest for member `...' is ambiguous in g++
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  1. POrequest for member `...' is ambiguous in g++
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    copied!<p>I'm getting the following compile error in one of my classes, using gcc 3.4.5 (mingw): </p> <pre><code>src/ModelTester/CModelTesterGui.cpp:1308: error: request for member `addListener' is ambiguous include/utility/ISource.h:26: error: candidates are: void utility::ISource&lt;T&gt;::addListener(utility::IListener&lt;T&gt;*) [with T = const SConsolePacket&amp;] include/utility/ISource.h:26: error: void utility::ISource&lt;T&gt;::addListener(utility::IListener&lt;T&gt;*) [with T = const SControlPacket&amp;] </code></pre> <p>Hopefully you can see that <code>ISource&lt;T&gt;</code> is a template interface that just indicates that the object can be an informer for an object that is of some matching type <code>IListener&lt;T&gt;</code>. So the thing that has me irked is this idea that for some reason functions are ambiguous when, as far as I can tell, they are not. The <code>addListener()</code> method is overloaded for different input types <code>IListener&lt;const SConsolePacket&amp;&gt;</code> and <code>IListener&lt;const SControlPacket&amp;&gt;</code>. The usage is:</p> <pre><code>m_controller-&gt;addListener( m_model ); </code></pre> <p>Where <code>m_model</code> is a pointer to an <code>IRigidBody</code> object, and <code>IRigidBody</code> inherits only from <code>IListener&lt; const SControlPacket&amp; &gt;</code> and definately not from <code>IListener&lt; const SConsolePacket&amp; &gt;</code></p> <p>As a sanity check, I used doxygen to generate the class hierarchy diagram and doxygen agrees with me that <code>IRigidBody</code> does not derive from <code>IListener&lt; const SConsolePacket&amp; &gt;</code></p> <p>Evidently my understanding of inheritence in c++ is not exactly correct. I'm under the impression that <code>IListener&lt;const SControlPacket&amp;&gt;</code> and <code>IListener&lt;const SConsolePacket&amp;&gt;</code> are two different types, and that the function declarations </p> <pre><code>addListener(IListener&lt;const SConsolePacket&amp;&gt;* listener) </code></pre> <p>and</p> <pre><code>addListener(IListener&lt;const SControlPacket&amp;&gt;* listener) </code></pre> <p>declare two separate functions that do two separate things depending on the (distinct) different type of the parameter that is input. Furthermore, I'm under the impression that a pointer to an <code>IRigidBody</code> is also a pointer to an <code>IListener&lt;const SControlPacket&amp;&gt;</code> and that by calling <code>addListener( m_model )</code> the compiler should understand that I'm calling the second of the above two functions.</p> <p>I even tried casting <code>m_model</code> like this:</p> <pre><code>m_controller-&gt;addListener( static_cast&lt;IListener&lt;const SControlPacket&amp;&gt;*&gt;(m_model) ); </code></pre> <p>but still get that error. I cannot for the life of me see how these functions are ambiguous. Can anyone shed light on this issue?</p> <p>P.S. I know how to force the function to be un-ambiguous by doing this:</p> <pre><code>m_controller-&gt;ISource&lt;const SControlPacket&amp;&gt;::addListener( m_model ); </code></pre> <p>I just happen to think that is terribly unreadible and I would prefer not to have to do that.</p> <p>Edit... just kidding. That apparently doesn't fix the problem as it leads to a linker error:</p> <pre><code>CModelTesterGui.cpp:1312: undefined reference to `utility::ISource&lt;aerobat::SControlPacket const&amp;&gt;::addListener(utility::IListener&lt;SControlPacket const&amp;&gt;*)' </code></pre>
 

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