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To: Rasmus Lerdorf <rasmus@lerdorf.com>
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Date: Fri, 16 Nov 2007 23:39:54 -0500
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Subject: Re: [PHP-DEV] Re: Question about superglobals
From: sam@sambarrow.com (Sam Barrow)

I disagree, although you do have a very good point. But simple logic
flaws can cause huge bugs regardless, whether it would be because of a
superglobal or any other programmer error. Although you have a point,
the only place where we disagree is that I think the benefits outweigh
the risks.

On Fri, 2007-11-16 at 20:34 -0800, Rasmus Lerdorf wrote:
> Sam Barrow wrote:
> > You say that superglobals were not designed to be user defined, think
> > about it, the concept of a superglobal is present in C and C++, two of
> > the maturest and strictest languages around.
> 
> The concept of having to declare your globals is unique to PHP, true.
> It is one of the oldest features in PHP too.  So, a little history...
> 
> Back in 1989 I spent at least a month chasing a bug at a company in
> Canada called Bell Northern Research.  It was a weird crash bug in a
> rather complicated system.  It was mostly written in C and after pouring
> through reams and reams of code printouts day after day, I finally found
> that it was due to a side effect of some obscure function overwriting a
> global variable that was used in a completely different area of the
> code.  That particular feature of the C language was not popular with me
> for a long time after that, and when it came time to work out function
> scoping of variables in PHP, I made sure to not make that same mistake.
> 
> And yes, because PHP is a web language and there are common aspects of a
> web request that many functions will need to act on, it makes sense to
> have a finite number of clearly labeled global arrays like _GET, _POST,
> etc.  And later on, being able to access any global via $_GLOBALS was
> added, but again, it is a very descriptive name and not likely to result
> in someone mistaking it for something else and ending up with strange
> side effects.
> 
> I am definitely not in favor of destroying what I consider a rather good
> design decision just to avoid a couple of keystrokes here and there.  So
> yes, you will have to keep adding "global $cfg;" to your functions, or
> accessing it via $_GLOBALS['cfg'], and when you forget, it won't work.
> And yes, you will grumble a bit at that, but that is nothing compared to
> trying to find a bug caused by a global side effect in someone else's
> code.  Trust me, you will grumble a lot more at that.
> 
> -Rasmus
>