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Date: Fri, 18 Sep 2015 19:24:57 +0100
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Subject: Re: [PHP-DEV] PHP 7.1 - Address PHPSadness #28?
From: rowan.collins@gmail.com (Rowan Collins)

Robert Williams wrote on 18/09/2015 18:40:
> Exactly, there’s clearly a gap here. Further, enough people want it 
> that a few have shown up on this list, which means there are probably 
> many, many thousands, or even millions, of people out in the wild that 
> want it. 

The problem is that a lot of the people that think they want it, don't 
actually have a use for it, they just feel like it "should" exist.

There are a couple of small edge cases that people have come up with 
during this thread where it's valid, but the vast majority of examples 
I've seen are simply misunderstanding what isset() does and why, or not 
realising that array_key_exists() and property_exists() already do the 
job they need.

The use cases Lester and yourself have come up with are NOT evidence 
that isset() is broken, as many people claim. They are things which the 
majority of people will never need to (arguably nobody "needs" to do 
them, but you want to do them, so I guess that's kind of the same thing).


> I’m not familiar enough with PHP’s internals to say for sure, but I 
> suspect it’s not terribly hard to implement (it’s just isset() without 
> the extra null check). So… why not? Like anything else in the 
> language, people don’t have to use it if they don’t want to, but it’s 
> good to have tools. Yes, even tools that can be abused.

Sure, I'm happy with that argument - IF we come up with a name and 
documentation that doesn't imply this is a replacement for isset(), or 
validate the incorrect conception that isset() is "broken".

The title of this thread refers to one such misunderstanding - the 
article at http://www.phpsadness.com/sad/28 waffles on a lot about 
empty() being a bad name, doesn't even mention isset(), and scares the 
user with a blob of C code, but doesn't really explain why any of this 
is a problem. It even says:

 > Some languages circumvent this issue by requiring variable 
declaration or giving undefined variables explicit values.

Neatly, PHP does both: if you take Notices seriously, variable 
declaration (or at least initialisation-before-reading) is required; if 
you ignore them, or use isset()/empty(), it gives the undefined variable 
a value of Null. :)


So, by all means, propose a function which searches the symbol table for 
a variable, but please don't call it something as generic as exists(), 
and please don't edit the isset() documentation to recommend its usage 
in any but the most unusual cases.

Regards,
-- 
Rowan Collins
[IMSoP]