The Note You're Voting On
sneskid at hotmail dot com ¶17 years ago
in addition to what 'jw at jwscripts dot com' wrote about unset; it can also be used to "detach" the variable alias so that it may work on a unique piece of memory again.
here's an example
<?php
define('NL', "\r\n");
$v1 = 'shared';
$v2 = &$v1;
$v3 = &$v2;
$v4 = &$v3;
echo 'before:'.NL;
echo 'v1=' . $v1 . NL;
echo 'v2=' . $v2 . NL;
echo 'v3=' . $v3 . NL;
echo 'v4=' . $v4 . NL;
$detach = $v1;
unset($v1);
$v1 = $detach;
eval(detach('$v2'));
$v1 .= '?';
$v2 .= ' no more';
$v3 .= ' sti';
$v4 .= 'll';
echo NL.'after:'.NL;
echo 'v1=' . $v1 . NL;
echo 'v2=' . $v2 . NL;
echo 'v3=' . $v3 . NL;
echo 'v4=' . $v4 . NL;
function detach($v) {
$e = '$detach = ' . $v . ';';
$e .= 'unset('.$v.');';
$e .= $v . ' = $detach;';
return $e;
}
?>
output {
before:
v1=shared
v2=shared
v3=shared
v4=shared
after:
v1=shared?
v2=shared no more
v3=shared still
v4=shared still
}
http://www.obdev.at/developers/articles/00002.html says there's no such thing as an "object reference" in PHP, but with detaching it becomes possible.
Hopefully detach, or something like it, will become a language construct in the future.
