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Thread-Topic: [PHP-DEV] PHP 7.1 - Address PHPSadness #28?
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Date: Wed, 16 Sep 2015 19:56:22 +0000
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Subject: Re: [PHP-DEV] PHP 7.1 - Address PHPSadness #28?
From: rewilliams@thesba.com (Robert Williams)

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On Sep 16, 2015, at 11:14, Rowan Collins <rowan.collins@gmail.com> =
wrote:
>=20
> Robert Williams wrote on 16/09/2015 18:37:
>> The docs suggest that uninitialized variables are null, and the above =
makes it sound like that=92s what you=92re stating, too. But they=92re =
not: they don=92t exist at all, they=92re uninitialized.
>=20
> As soon as you access them, you will get the value null. You can do =
everything with them that you could do with a variable initialised to =
null.

As soon as you access them, you get an error, and then you get null. =
Yeah, one could register an error handler, but that=92s a lot of fuss =
just to see if a variable really exists or just exists because you =
accessed it, and it pulls you out of context. Basically, there=92s no =
(clean, very simple) way to identify that you=92re about to step in a =
pile of poo before you step in it.

>> If they were null, then PHP wouldn=92t spit out errors about =
undefined variable accesses
>=20
> Once again - PHP does not spit out errors when you access an undefined =
variable. It spits out Notices in case you've done it by mistake. Maybe =
you're thinking of JavaScript?

In our shop, notices are most definitely errors. And notices aren=92t =
graceful error handling. I think PHP also also regards them as errors =
(thus the ability to catch them with an error handler) - it=92s just a =
lower grade of error.

> I don=92t think it=92s a huge gap in the language, but it=92s a =
definite gap, and it=92s one that many less-experienced programmers fall =
right into with safety checks.
>=20
> There is no safety check required. If you care about eliminating the =
Notices, then initialise all your variables properly, and you will never =
have an uninitialised variable (so a runtime check for one would be =
pointless). If you don't care about eliminating the Notices, then simply =
treat uninitialised variables as Null, and they will work absolutely =
fine.


That=92s great in theory, but in practice, programmers=92 code must =
frequently collaborate with other people=92s code, often code from =
outside their organization. In these cases, they don=92t have the =
control to just fix the problem on the other side. And in some cases, =
like with config files that set bare variables, there=92s really nothing =
wrong with the way it=92s done that needs to be fixed. Some folks might =
prefer to use a different model, but that=92s just a preference.

Adding an exists() function doesn=92t go against the foundation of PHP. =
It just fills a gap. Again, I can define variables, and I can destroy =
them, but I can=92t tell if they=92ve already been defined. In a dynamic =
language like PHP, I really don=92t understand how folks can *not* see =
that as an oversight. Further, we can do this for everything else=85 =
constants, array elements, object properties, functions, and even =
classes, so why not variables? There's even have precedence for =
controlling behavior based on variable existence in extract(), so PHP =
itself does it in ways that directly affect the user, but the user can=92t=
 do it. Yes, there are workarounds for the gap. There are almost always =
workarounds in a sufficiently developed language, but that doesn=92t =
mean there isn=92t a gap.

-Bob

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