W3C home > Mailing lists > Public > public-html@w3.org > July 2009

Re: PHP code only allowed in XHTML 5?

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Wed, 29 Jul 2009 14:05:28 +0200
Message-ID: <4A703B08.9050008@lachy.id.au>
To: Daniel Glazman <daniel.glazman@disruptive-innovations.com>
Cc: public-html <public-html@w3.org>
Daniel Glazman wrote:
> Toby A Inkster wrote:
>
>> <p class="<?php echo 'foo';?>">
>>
>> Invalid in both XHTML and HTML, but perfectly legal PHP. PHP's start
>> and end markers are not real XML processing instructions. They just
>> look a bit like them.
>
> They are real processing instructions and the current PHP start marker
> <?php was not the one early versions of PHP used. It was changed to
> match SGML/XML PIs to allow editability in markup editors and wysiwyg
> editors.

No, while it has been successfully demonstrated that the chosen syntax 
was largely inspired by PIs, PHP itself does not use either SGML or XML 
processing and, as shown multiple times in this thread, does not even 
fully conform with the syntax of either.  Pretending otherwise doesn't 
do anyone any good.

Rather, PHP's use of the <?php ?> syntax (and the older <? ?> syntax) is 
simply analogous to ASP's and JSP's use of the <% %> syntax.  It's a 
distinct syntax that can be used together with HTML/XML fragments, that 
requires pre-processing in order to output either.

Although, PHP certainly isn't limited to outputting just HTML or XML, it 
can output anything.  Are you concerned that the <?php ?> syntax is 
invalid in CSS, though it can quite easily be used to output CSS files 
like this?

<?php
header("Content-Type: text/css; charset=UTF-8");
$mycolor = "#F63"
?>
h1 { color: <?php echo $mycolor; ?>; }
...

Why should it matter that <?php ?> is technically invalid HTML/XML, but 
not that it's also invalid CSS, JS, or any other language?

> Breaking that compatibility is, IMHO, a serious error.

We're not breaking compatibility.  PHP never had any real compatibility, 
in the sense you are claiming, with HTML, SGML or XML.  We're just 
clearing up the fiction about PHP itself being conforming HTML, or even 
SGML or XML for that matter.

-- 
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/
Received on Wednesday, 29 July 2009 12:06:11 GMT

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