Req #21353 [Opn->Bgs]: Functions for using references

Edit report at http://bugs.php.net/bug.php?id=21353&edit=1 ID: 21353 Updated by: johannes@php.net Reported by: aulbach at ssilk dot de Summary: Functions for using references -Status: Open +Status: Bogus Type: Feature/Change Request -Package: Feature/Change Request +Package: *General Issues PHP Version: 4.3.0 Block user comment: N Private report: N New Comment: foreach ( $array as &$value ) is implemented references_unset() / references_all() would require a massive re-design as we don't have proper global variable lists. Use of references is discouraged anyways. Previous Comments: ------------------------------------------------------------------------ [2003-01-02 15:22:59] aulbach at ssilk dot de In my opinion there are some functions missing in PHP, depending the handling of references. I found out, that it isn't possible to find out, if and what other variables references to my value. But this is sometimes important, especially for very complex scripts or self-configuring. So I would suggest the following new functions: - references() (or perhaps better references_of() which is more meaningful) - returns an array of all referenced variables, exept the current. false, if it has no other references print_r( references($b) ); should output "array('a')", this means $b has in it's local and/or global scope the reference $a. Hm, maybe it's important to differ local and global, so a second parameter with the defined values REFERENCES_LOCAL etc. Could be fine. Maybe it's difficult to output referenced variables which are objects or arrays... I have currently no idea how to do that consequently and easy: $a=array(0=>1); $b=&$a[0]; print_r(references($b)); ... should output what?? array('a'=>array('0')) or array('a[0]')?? (btw: In the case of the second option the following feature would be very nice (I have been missing this sometimes, but don't know if this is currently working): $c='a[0]'; $$c='hugo'; echo $a[0]; -> outputs 'hugo' ) - references_all() (or perhaps better all_references() ?)- This is like references(), but returns ALL references, including the parameter. So it should return always an array. This is good to build a loop here, see down. - is_referenced() or perhaps referenced_num() - returns true or better the number of references of this variable to the VALUE (without counting itself) $a=1; $b=&$a; echo referenced_num($a); echo referenced_num($b); should both output '1' - unset_references() - unsets all references to the VALUE of a variable, with this you can be sure, that storage of this value is cleaned up, even, if you are in a local scope like function bla() { global $a; unset_references($a); } $a='hugo' bla(); # $a is unset This is not the very same as setting the VALUE to the value NULL ($a=null;), where the references to $a will survive. It really unsets all references to the value unsets, it is just like it has never been set before, which means, that unset_references($a); echo $b; (should consequently output a notice, that $b never has been set in the script...) A gimmick to be consequent unset_references(&$var) should be the same as unset($var) and deletes only the REFERENCE $var. Indeed unset_references($a); is maybe the same (?) as: foreach ( all_references($a) as $v ) { unset_references(&$$v); } Looks very cool. :-) Another good name alias would be unset_value(), cause it also unsets the value, or more simply clean() or purge(). - There may be some other features depending references, like foreach ( $array as &$value ) which will call the loop var $value by reference instead by value (think this could be easy to implement). - The documentation should be rewritten in some parts. My experience brought out, that it's fine to distinguish better between * VARIABLE (= *always* a REFERENCE, or POINTER to a VALUE, unlike C, PHP cannot directly hold VALUES in a VARIABLE) and * VALUE (= STORAGEPLACE of a VARIABLE, a VALUE can have many VARIABLES or REFERENCES) The documentation here is based on PHP3, in PHP4 many things has changed, so it's a little "wrong" in some parts (see my comment to the function unset())... This would make many things more clearly for beginners - I saw this with our trainees here: When I explained, that a variable is always only a reference to a value they said all "ah, ja, that is it, this is missing in the docs"... :-) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=21353&edit=1