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POLazy evaluation on templated function parameter
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  1. POLazy evaluation on templated function parameter
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    copied!<p>I have a class for logging, which MUST NOT inherit std::ostream, and has operator&lt;&lt; defined for the same types as the standard output stream PLUS a templated version:</p> <pre><code>class MyLoggingClass { [...] public: template&lt;typename T&gt; MyLoggingClass &amp; operator&lt;&lt;( T&amp; data ){ ... } } </code></pre> <p>Also, for every printable class in my program, I have the typical non-member function defined:</p> <pre><code>std::ostream &amp; operator &lt;&lt; ( std::ostream &amp; os, const OneOfMyClasses &amp; foo ); </code></pre> <p>The thing is that, internally, my logger sometimes uses an standard output stream, this is:</p> <pre><code>template&lt;typename T&gt; MyLoggingClass &amp; operator&lt;&lt;( T&amp; data ) { [...] if( someCondition ) { cout &lt;&lt; data; } [...] } </code></pre> <p>Thanks to this, I can log my classes without explicitly replicating on every of them the non-member operator&lt;&lt; for MyLoggingClass. The problem comes in a line where I try to log an object created "on the fly":</p> <pre><code>MyLoggingClass logger; logger &lt;&lt; OneOfMyClasses(params); // Here I am invoking the constructor of class "OneOfMyClasses" </code></pre> <p>The thing is that, instead of invoking the constructor, and then passing the object as parameter of the operator&lt;&lt;, it interprets that I'm trying to log a pointer to function.</p> <p>Of course, some valid solutions for this problem include:</p> <ul> <li>Removing the templated operator&lt;&lt;, and making MyLoggingClass extend std::ostream</li> <li>Removing the templated operator&lt;&lt;, and creating tons of non-member operator&lt;&lt;( MyLoggingClass &amp;, const OneOfMyClasses &amp; )</li> <li>Storing the object to log in a temporal variable, and then doing "logger &lt;&lt; temporalObject;" However, I would like to know if there is a way to force the compiler evaluating the constructor call. Do you know any workaround for this case?</li> </ul> <p>Thank you in advance for your time :)</p>
 

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