RE: [PHP] Object and reference problem

You're not passing by reference. Change: function add($child) { $this->children[] = $child; } to function add(&$child) { $this->children[] = &$child; } This should work. When you pass an object as a parameter PHP makes a copy of that object as a local instance in your method. So, your original code: 4 $obj2->add(", something else"); 5 $obj1->add($obj2); would alter $obj2 and store a copy of that altered object in $obj1. But, 5 $obj1->add($obj2); 4 $obj2->add(", something else"); would store a copy of unaltered $obj2 in $obj1. You'd then alter a different instance of $obj2 in the succeeding line. By using the suggested altered code at the top of this email, line 5 would not pass a copy but would pass a reference to the actual instance of the object. Note, you also have to ensure that you store a reference to this guy in your array as by default adding items to arrays causes copies to be made. So you also need the line: $this->children[] = &$child; Hope this helps. > -----Original Message----- > From: Brian White [mailto:bwhite@steptwo.com.au] > Sent: 17 October 2001 04:41 > To: SafeV; php-general@lists.php.net > Subject: Re: [PHP] Object and reference problem > > > I think you are going to have to live with it. > > Functional overloading only really makes sense in strongly typed > languages, and I bet is a bugger to implement in a name based > scripting language so I don't think you are goign to get it. > > What I have sometimes wished for was that all objects and arrays > were passed around as pointers by default, with the ability > to create a copy when required, but that is such a fundamental > change that I doubt if it will happen, and there are probably > goo reasons not to ( have I ever told people how much I like > Python ... ) > > Maybe you are just going to have to bite the bullet and have > an "AddRef" method...... > > > At 04:28 17/10/2001 +0200, SafeV wrote: > >Someone, have a go at this! > > > >I have encountered a very troublesome problem, which I don't see how to > >solve in an elegant way, since PHP doesn't support method overloading. > > > >Suppose my class is, kind of a tree, like: > > > >class A { > > var $children; > > > > function A() { > > $this->children = array(); > > } > > > > // I want this to accept both objects and strings etc. > > // IE. mixed > > function add($child) { > > $this->children[] = $child; > > } > > > > function printStuff() { > > foreach ($this->children as $child) { > > if (is_object($child)) > > $child->printStuff(); > > else > > echo $child; > > } > > } > >} > > > >Now this is fine: > > > >1 $obj1 = new A(); > >2 $obj2 = new A(); > >3 $obj1->add("Something"); > >4 $obj2->add(", something else"); > >5 $obj1->add($obj2); > >6 $obj1->printStuff(); > > > >and prints out "something, something else" > > > >But if I swap lines 4 and 5 it only prints out "something". > >Obviously, the add method of $obj1 only receives a copy of $obj2, and > >if I try to add something to $obj2 afterwards, even thought it's > supposed > >to be hooked with $obj1, it will "disappear". > > > >For objects only I could solve this with declaring add() like: > >function add(&$child) { > > $this->children[] = $child; > >} > >So it receives a reference of the object, but then I can't add a string > >(fatal error, cannot pass string as reference), or an integer or double, > >for that matter! And I really don't want to use different method names! > > > >I don't have full control over the reference stuff in PHP, does anyone > >know how I can fix this? Or a workaround? > > > >Thanx! > > > > > >-- > >PHP General Mailing List (http://www.php.net/) > >To unsubscribe, e-mail: php-general-unsubscribe@lists.php.net > >For additional commands, e-mail: php-general-help@lists.php.net > >To contact the list administrators, e-mail: php-list-admin@lists.php.net > > ------------------------- > Brian White > Step Two Designs Pty Ltd - SGML, XML & HTML Consultancy > Phone: +612-93197901 > Web: http://www.steptwo.com.au/ > Email: bwhite@steptwo.com.au > > > -- > PHP General Mailing List (http://www.php.net/) > To unsubscribe, e-mail: php-general-unsubscribe@lists.php.net > For additional commands, e-mail: php-general-help@lists.php.net > To contact the list administrators, e-mail: php-list-admin@lists.php.net