note 101381 added to class.iterator

For Iterators implement database queries, what I've found is that if you want to chain multiple iterators together using a "MultipleIterator" then you *do not* want ::rewind() to actually execute your query, especially if it's expensive. Instead, what I've done is implement that portion in "valid." e.g. <?php class Database_Result_Iterator { ... private $_db_resource = null; private $_loaded = false; private $_valid = false; function rewind() { if ($this->_db_resource) { mysql_free($this->_db_resource); $this->_db_resource = null; } $this->_loaded = false; $this->_valid = false; } function valid() { if ($this->_loaded) { $this->load(); } return $this->_valid; } private function load() { $this->_db_resource = mysql_query(...); $this->_loaded = true; $this->next(); // Sets _valid } } ?> That way if you chain multiple queries in a "MultipleIterator" together, the "rewind" call (which rewinds all iterators at once) does not execute every query at once. In addition, I found that the MultipleIterator may now work best for other reasons, but still, the above is a good idea to postpone queries until the last possible moment they are needed. ---- Server IP: 64.71.164.2 Probable Submitter: 96.245.89.9 ---- Manual Page -- http://www.php.net/manual/en/class.iterator.php Edit -- https://master.php.net/note/edit/101381 Del: integrated -- https://master.php.net/note/delete/101381/integrated Del: useless -- https://master.php.net/note/delete/101381/useless Del: bad code -- https://master.php.net/note/delete/101381/bad+code Del: spam -- https://master.php.net/note/delete/101381/spam Del: non-english -- https://master.php.net/note/delete/101381/non-english Del: in docs -- https://master.php.net/note/delete/101381/in+docs Del: other reasons-- https://master.php.net/note/delete/101381 Reject -- https://master.php.net/note/reject/101381 Search -- https://master.php.net/manage/user-notes.php