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POWhy does PHP's call_user_func() function not support passing by reference?
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copied!<p>Why don't the function handling functions like <code>call_user_func()</code> support passing parameters by reference?</p> <p>The <a href="http://php.net/call_user_func">docs</a> say terse things like "Note that the parameters for call_user_func() are not passed by reference." I assume the PHP devs had some kind of reason for disabling that capability in this case.</p> <p>Were they facing a technical limitation? Was it a language design choice? How did this come about?</p> <p>EDIT:</p> <p>In order to clarify this, here is an example.</p> <pre><code><?php function more(&$var){ $var++; } $count = 0; print "The count is $count.\n"; more($count); print "The count is $count.\n"; call_user_func('more', $count); print "The count is $count.\n"; // Output: // The count is 0. // The count is 1. // The count is 1. </code></pre> <p>This is functioning normally; call_user_func does not pass $count by reference, even though more() declared it as a referenced variable. The <a href="http://php.net/call_user_func">call_user_func documentation</a> clearly says that this is the way it's supposed to work.</p> <p>I am well aware that I can get the effect I need by using <code>call_user_func_array('more', array(&$count))</code>.</p> <p>The question is: why was call_user_func <strong>designed</strong> to work this way? The <a href="http://php.net/manual/en/language.references.pass.php">passing by reference documentation</a> says that "Function definitions alone are enough to correctly pass the argument by reference." The behavior of call_user_func is an exception to that. Why?</p>

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