How do you break a reference to a variable in PHP without destroying the variable itself?
I have written a PHP loop that stores a reference to objects in $GLOBALS['parent_variables'] and then destroy it at the end of the function.
The function is called in the loop. I assume I use:
unset($GLOBALS['parent_variables'])
Does that destroy the reference? Just to confirm...
I set the reference like this:
$GLOBALS['parent_variables'] = &$question->variables;
After:
$GLOBALS['parent_variables'] = &$question->variables;
Using:
unset($GLOBALS['parent_variables'])
... will break the reference -- as in set $parent_variables to null, while keeping $question->variables.
Using:
$GLOBALS['parent_variables'] = null
... will set both variables to null.
Example:
$foo = 'bar';
$GLOBALS['baz'] = &$foo;
unset($GLOBALS['baz']);
var_dump($GLOBALS['baz'], $foo); # null, bar; undefined index notice for baz
$GLOBALS['baz'] = &$foo;
$GLOBALS['baz'] = null;
var_dump($GLOBALS['baz'], $foo); # null, null; no notice (since baz is set)
Unsetting from the array does only remove the 'reference' and does not change the original object you copied from. Example:
<?php
$foo = new StdClass();
$foo->bar = "hello";
$_FAKE_GLOBAL_ARRAY = array();
$_FAKE_GLOBAL_ARRAY['foo'] = $foo->bar;
echo "array references ".$_FAKE_GLOBAL_ARRAY['foo'];
echo "<br>object contains ".$foo->bar;
unset($_FAKE_GLOBAL_ARRAY['foo']);
echo "<br>now array references ".(isset($_FAKE_GLOBAL_ARRAY['foo']) ? $_FAKE_GLOBAL_ARRAY['foo'] : " nothing");
echo "<br>now object contains ".$foo->bar;
?>
outputs
array references hello
object contains hello
now array references nothing
now object contains hello