note 75353 deleted from language.references.spot by danbrown

Note Submitter: Mildred 

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Someone said that BenBe's function is_ref() was broken for testing objects. I didn't test it but I rewrote it and I know it works for objects. Here is the new version :

<?php
function is_ref(&$a, &$b){

    if(gettype($a) !== gettype($b)) return false;

    $same = false;
    if(is_array($a)){

        //Look for an unused index in $a
        $key = uniqid("is_ref_", true);
        while(isset($a[$key]))$key = uniqid("is_ref_", true);

        //The two variables differ in content ... They can't be the same
        if(isset($b[$key])) return false;

        //The arrays point to the same data if changes are reflected in $b
        $data = uniqid("is_ref_data_", true);
        $a[$key] =& $data;
        //There seems to be a modification ...
        $same = ((isset($b[$key])) and ($b[$key] === $data));

        //Undo our changes ...
        unset($a[$key]);

    }elseif(is_object($a)){

        //The same objects are required to have equal class names ;-)
        if(get_class($a) !== get_class($b)) return false;

        //Look for an unused property in $a
        $key = uniqid("is_ref_", true);
        while(isset($a->$key))$key = uniqid("is_ref_", true);

        //The two variables differ in content ... They can't be the same
        if(isset($b->$key)) return false;

        //The arrays point to the same data if changes are reflected in $b
        $data = uniqid("is_ref_data_", true);
        $a->$key =& $data;
        //There seems to be a modification ...
        $same = ((isset($b->$key)) and ($b->$key === $data));

        //Undo our changes ...
        unset($a->$key);

    }elseif(is_resource($a)){

        if(get_resource_type($a) !== get_resource_type($b))return false;
        $same = ((string) $var1) === ((string) $var2);

    }else{

        if($a !== $b) return false;

        //To check for a reference of a variable with simple type
        //simply store its old value and check against modifications of the second variable ;-)

        $data = uniqid("is_ref_", true);
        while($data === $a) $data = uniqid("is_ref_", true);

        $save = $a;             //WE NEED A COPY HERE!!!
        $a    = $data;          //Set a to the value of $data (copy)
        $same = ($a === $b);    //Check if $var2 was modified too ...
        $a    = $save;          //Undo our changes ...

    }
    return $same;
}
?>