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To: Stanislav Malyshev <smalyshev@gmail.com>
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Thread-Topic: [PHP-DEV] PHP 7.1 - Address PHPSadness #28?
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Date: Thu, 17 Sep 2015 01:17:59 +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 14:57, Stanislav Malyshev <smalyshev@gmail.com> =
wrote:
>=20
>> I=92ll refer again to the above documentation:
>>=20
>> "A variable is considered to be null if [=85] it has been unset().=94
>=20
> You are confusing two things.
>=20
> 1. The variable has value of null.
> 2. The variable does not exist, so when you try to get its value,
> there's nothing to give you, but we don't want to produce fatal error
> because of such trifle, so we substitute null instead.

Nothing confused here. If the variable doesn=92t exist, then it doesn=92t =
exist, and accessing it rightly produces an error (albeit a low-grade =
error). PHP gives you a token null to be nice, but the fact is, you =
still committed an error by trying to access something that doesn=92t =
exist. I=92m fine with all of that, but I also would like to have the =
option of easily knowing about the problem before I hit it.

And, although you may not care whether the provenance of a variable=92s =
null lies in buggy code or in explicit programmer/user decision, I =
consider that an extremely important distinction. It=92s the difference =
between, =93What the hell, delete anyway. They can always do the work =
again.=94 and, =93Okay, we=92ve got a signed delete order from the user, =
so delete away."

>> This one can=92t be chalked up to sloppy writing. Here, something is =
just
>> plain wrong.
>=20
> I'm afraid the something which is wrong here is your understanding of
> how undefined variables and nulls work :) "Considered to" is not the
> same as "is". It's a substitution, not identity.

I understand it just fine, thank you, but I disagree with your =
forgiveness of the docs. An unset variable is not null. Rather, it=92s =
completely undefined, and PHP yells at you for just that reason if you =
try to access it. Then, it turns around and tries to appease you by =
giving you null. If it changed it to null on access and never threw the =
error, your statement would be more accurate, but that=92s not what =
happens.

For the record, I=92d actually prefer that PHP throw a fatal error if =
you access an undefined variable because it almost always means that =
your code is working with junk data. Right along with that, however, I=92d=
 like a way to easily tell that my data is bad (i.e., a variable hasn=92t =
been defined) so that I can gracefully handle the problem and avoid the =
fatal.

-Bob

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