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To: Philip Olson <philip@roshambo.org>
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Date: Wed, 17 Mar 2010 00:23:33 +0100
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Subject: Re: [PHP-DEV] PHP 6
From: foolistbar@googlemail.com (Geoffrey Sneddon)


On 12 Mar 2010, at 20:15, Philip Olson wrote:

>
> On Mar 12, 2010, at 10:46 AM, Stanislav Malyshev wrote:
>
>> Hi!
>>
>>> Yeah.
>>> We tried it, and it simply didn't pan out (performance, bc, lost  
>>> interest, ..).
>>
>> I think it is a bit premature to declare the death of Unicode in  
>> PHP. Yes, we know there are problems, and yes, it was harder that  
>> initially thought, so we may want to take a step back and rethink  
>> it. Also we may want to get Unicode out of the way of other PHP  
>> development, since it's taking longer than planned. But that  
>> doesn't mean we should bury it.
>
> How have other languages progressed down the unicode road? Is there  
> anything we can learn from their progress over these past few years?

 From all the languages that I've had dealings with, only Python has  
attempted anything like the previous PHP 6 attempt. Ruby's move to a  
certain level of Unicode support in 1.9 is interesting, though I'm not  
entirely sure that's been out for long enough to draw any real  
conclusions about uptake of it from.

I think the most important thing learnt from the Python case is that  
backwards compatibility is paramount, and trying to break backwards  
compatibility with programmatic conversion to the new language version  
is hard to gather uptake on, yet alone what happened with the old PHP6  
branch, which would've broken large amounts of applications with no  
way to programmatically convert code to it.

Python 2 had no problem getting uptake where Unicode strings need to  
be specifically marked (e.g., u"foo" as opposed to "foo"), yet Python  
3 (which can mostly be programmatically converted from Python 2) has  
had comparatively little uptake due to its incompatibility.

So, let me start with what I want to be true of PHP 6: anything that  
runs under PHP 5.3 and does not throw any errors (with E_ALL |  
E_DEPRECATED) must behave identically under PHP 6.

That single statement has quite a lot of consequences, but, with  
regards to Unicode, one thing more than anything else: Unicode strings  
cannot be the default. I have plenty of code that uses UTF-8 in some  
strings and arbitrary binary data in others. I want to be able to move  
to PHP 6 gradually: I shouldn't have to wait for every library I rely  
upon to be modified for PHP 6 compatibility. I should just be able to  
move to PHP 6, and look over my own code and change what strings I  
want to Unicode strings.

To point out what should be obvious to everyone here: one of the  
biggest strengths of PHP is the large amount of library and  
applications already written for it. Making a large, backwards  
incompatible change such as making Unicode strings the default would  
not only limit adoption to those who have entirely new code, but also  
alienate most shared-hosting providers who cannot afford to break  
their clients code because of a backwards incompatible change that'll  
break everyone's applications.

If there's one thing I've learnt from working on browsers for the past  
few years it's that backwards compatibility is more valuable than  
something new and shiny. I have no doubt PHP needs Unicode support,  
but I don't think that breaking backwards compatibility for it is the  
right solution. The fact that PHP is deployed as it is, often in  
shared hosting setups, should very much be a reason to be concerned  
for backwards compatibility. A browser would get almost no marketshare  
if it broke a large percentage of existing websites; I believe the  
same to be true of PHP with the websites it powers.


--
Geoffrey Sneddon
<http://gsnedders.com/>