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POShould all C++ functions be declared taking rvalue from now?
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  1. POShould all C++ functions be declared taking rvalue from now?
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    copied!<p>Why should I or shouldn't I create all my functions and members functions to take a <code>rvalue</code> and leave out versions that take a <code>lvalue</code>? You can always forward <code>lvalue</code> to rvalue, right? I can even have <code>const rvalue</code>, so why is this a bad idea, or a good idea?</p> <p>What I mean in code is below. The <code>"&amp;&amp;" rvalue</code> reference allows the users to use temporaries and can still use <code>lvalue</code> by a simple forward. So with this in mind, why should I provide <code>print_string(string&amp; str)</code> (<code>lvalue</code> reference) of any function in c++11 (besides <code>const</code> reference, because <code>rvalue</code> there is fine)?</p> <pre><code>#include &lt;iostream&gt; #include &lt;string&gt; #include &lt;utility&gt; using namespace std; void print_string(string&amp;&amp; str) { str += "!!!"; cout &lt;&lt; str &lt;&lt; endl; } void print_string2(string&amp; str) { str += "???"; cout &lt;&lt; str &lt;&lt; endl; } int main(int argc, char* argv[]) { print_string("hi there"); // works print_string(string("hi again")); // works string lvalue("lvalue"); print_string(forward&lt;string&gt;(lvalue)); // works as expected //print_string(lvalue); // compile error //print_string2("hi there"); // comile error //print_string2(string("hi again")); // compile error print_string2(lvalue); char a; cin &gt;&gt; a; } </code></pre> <h2>output</h2> <p>hi there!!! <br> hi again!!! <br> lvalue!!! <br> lvalue!!!???</p> <p><code>void print_string(string&amp;&amp; str)</code> provides a more flexible use case than <code>void print_string2(string&amp; str)</code> so why shouldn't we use rvalue arguments all the time?</p>
 

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