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POfunction overloading with a lot of arguments
 

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  1. POfunction overloading with a lot of arguments
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    <p>Say I have this constructor in C++:</p> <pre><code> A::A( std::string const&amp; name, std::string const&amp; type, std::vector&lt;B&gt; const&amp; b_vec, bool unique ) : _name(name), _type(type), _b_vec(b_vec), _unique(unique) { }; </code></pre> <p>I would like to overload this constructor for the case where the arguments are rvalues (I want to use move semantics there).</p> <pre><code> A::A( std::string &amp;&amp; name, std::string &amp;&amp; type, std::vector&lt;B&gt; &amp;&amp; b_vec, bool unique ) : _name(name), _type(type), _b_vec(b_vec), _unique(unique) { }; </code></pre> <p>The above one works fine when all of the arguments are rvalues, but suppose if only some of them are is in the next example:</p> <pre><code> // create some lvalues somehow std::string name = "stack overflow"; std::vector&lt;B&gt; vec = { ... }; // implementation of B's constructot is not important // call a mixed constructor A new_A_instance(name, "cool-website", vec, true); </code></pre> <p>it is to my understanding that since 'const&amp;' cannot bind to '&amp;&amp;' but '&amp;&amp;' can bind to 'const&amp;' the first (non-move) constructor would be used. </p> <p>This seems sub-optimal, since two of the four arguments could be moved (because they are rvalue) instead of being copied (as is the case in the first constructor).</p> <p>So I could overload the operator for this specific case, but one could easily image a case where other arguments are rvalue and others are agin lvalue. Should I overload the constructor for each of these cases? This would combinatorily lead to very much overloads as the number of arguments increases...</p> <p>I kind-of <em>feel</em> there is a better solution (perhaps using templates, but my template knowledge is shamefully low).</p> <p>Note: this problem isn't tied to overloading pass-by-ref functions to move functions per-se, but I found this a good example (especially since the overloads don't <em>feel</em> very different). Also note that I just used constructors as an example, but the overloaded function can be anything.</p>
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    1. COAn rvalue bool, as well as a `const bool`, are utterly pointless.
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    2. CO@Kerrek: I agree. Don't know why I put them there.
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      1. USromeovs
 

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