Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:8174
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Message-ID: <20040226160254.4324.qmail@pb1.pair.com>
To: internals@lists.php.net
Date: Thu, 26 Feb 2004 15:53:50 +0000
Lines: 25
Organization: Stutchbury
User-Agent: KNode/0.7.2
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7Bit
Subject: Iterator Class/foreach Logic Flaw?
From: philip@stutchbury.com (Philip Fletcher)

At the risk of making a complete fool of myself, I'd like to ask the smarter
brains than me to checkout the current logic in the implementation of
Iterator classes and foreach().

The current logic of foreach( $obj as $key => $val ) { ... } where $obj
implements Iterator, is:

for($obj->rewind(); $obj->hasMore(); $obj->next() ) { ... }

but it should be:

for($obj->rewind(); $obj->isValid(); $obj->next() ) { ... }

As the iterator exits the penultimate interation, next() is called, placing
the 'pointer' on the last 'record'. But before the last record is
processed, hasMore() is called, which *should* return FALSE, because we
have already moved to the last record.

The implementations I have seen so far all return TRUE from hasMore() when
positioned (i.e. current()) on the last record - this is not logical
(Captain). It also prevents proper use of a class implementing an iterator
outside of the foreach construct.

Philip