Newsgroups: php.internals Path: news.php.net Xref: news.php.net php.internals:32427 Return-Path: Mailing-List: contact internals-help@lists.php.net; run by ezmlm Delivered-To: mailing list internals@lists.php.net Received: (qmail 64589 invoked by uid 1010); 23 Sep 2007 19:00:28 -0000 Delivered-To: ezmlm-scan-internals@lists.php.net Delivered-To: ezmlm-internals@lists.php.net Received: (qmail 64574 invoked from network); 23 Sep 2007 19:00:28 -0000 Received: from unknown (HELO lists.php.net) (127.0.0.1) by localhost with SMTP; 23 Sep 2007 19:00:28 -0000 Authentication-Results: pb1.pair.com header.from=stas@zend.com; sender-id=pass Authentication-Results: pb1.pair.com smtp.mail=stas@zend.com; spf=pass; sender-id=pass Received-SPF: pass (pb1.pair.com: domain zend.com designates 212.25.124.162 as permitted sender) X-PHP-List-Original-Sender: stas@zend.com X-Host-Fingerprint: 212.25.124.162 mail.zend.com Windows 2000 SP4, XP SP1 Received: from [212.25.124.162] ([212.25.124.162:4397] helo=mx1.zend.com) by pb1.pair.com (ecelerity 2.1.1.9-wez r(12769M)) with ESMTP id D1/A9-30687-9C7B6F64 for ; Sun, 23 Sep 2007 15:00:28 -0400 Received: from us-ex1.zend.com ([192.168.16.5]) by mx1.zend.com with Microsoft SMTPSVC(6.0.3790.3959); Sun, 23 Sep 2007 21:04:09 +0200 Received: from [127.0.0.1] ([192.168.17.16]) by us-ex1.zend.com with Microsoft SMTPSVC(6.0.3790.1830); Sun, 23 Sep 2007 12:04:02 -0700 Message-ID: <46F6B7BE.4020205@zend.com> Date: Sun, 23 Sep 2007 12:00:14 -0700 Organization: Zend Technologies User-Agent: Thunderbird 2.0.0.6 (Windows/20070728) MIME-Version: 1.0 To: Paul Biggar CC: internals@lists.php.net References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 23 Sep 2007 19:04:02.0954 (UTC) FILETIME=[818B4EA0:01C7FE14] Subject: Re: [PHP-DEV] Compiled variables and backpatching From: stas@zend.com (Stanislav Malyshev) > What is a compiled variable? > How does it differ from a non-compiled-variable? When engine encounters variable like $a what it usually does is it looks up current symbol table for an entry named 'a', and then takes zval* sitting there. However, since during the same scope the entry for $a will be the same (though not a value sitting there!), once found in can be stored so future calls to $a will not require looking up in the hash table. That's what CVs do. The reason, of course, is performance :) -- Stanislav Malyshev, Zend Software Architect stas@zend.com http://www.zend.com/ (408)253-8829 MSN: stas@zend.com