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Date: Fri, 13 Apr 2012 15:37:38 +0200
Message-ID: <CACQesk5nvzkJjwJyJ7buKV2pqhgL_+HUuZxx6UuCdHpmJb_ziw@mail.gmail.com>
To: Nikita Popov <nikita.ppv@googlemail.com>
Cc: Pal Konyves <paul.konyves@gmail.com>, internals@lists.php.net
Content-Type: text/plain; charset=UTF-8
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Subject: Re: [PHP-DEV] Allow non-variable arguments to empty()
From: colder@php.net (Etienne Kneuss)

Hi,

On Fri, Apr 13, 2012 at 15:00, Nikita Popov <nikita.ppv@googlemail.com> wro=
te:
> On Fri, Apr 13, 2012 at 11:37 AM, Pal Konyves <paul.konyves@gmail.com> wr=
ote:
>> I don't see the point of empty( function() ).
>>
>> You tipically use empty on values that holds information you want to use
>> later in the program flow (a string, an integer). That means you'd bette=
r
>> extract it to a variable because you want to avoid calling twice a funct=
ion
>> that provides this value.
> You don't always need the value.
>
> Browsing around Google it seems that one of the most common source of
> the function call in write context error is people trying to do
> if(empty(trim($xyz)). You don't necessarily need the result of
> trim($xyz), so it's reasonable not to save it into a temporary
> variable.

well, empty(trim()) actually is a good example for when you don't want
to use empty(). People typically assume empty checks for the empty
string here, and it doesn't.

>
> Another example for example would be a function like this:
>
> public function isValid() {
> =C2=A0 =C2=A0if (...) { $this->addError('xyz'); }
> =C2=A0 =C2=A0if (...) { $this->addError('abc'); }
> =C2=A0 =C2=A0if (...) { $this->addError('foo'); }
> =C2=A0 =C2=A0if (...) { $this->addError('bar'); }
>
> =C2=A0 =C2=A0return empty($this->getErrors());
> }
>
> Furthermore you don't necessarily have to throw the return value away.
> For example I commonly write code like this:
>
> if (null =3D=3D=3D $result =3D $this->foo()) {
> =C2=A0 =C2=A0throw new Exception(...);
> }
> $result->doSomething();
>
> You can do something similar with empty():
>
> if (empty($values =3D $this->getValues()) {
> =C2=A0 =C2=A0return;
> }
> $this->doSomethingWith($values);
>
> I know, not everyone likes that kind of coding style, but I think it
> has it's uses.

I believe the change is good, but only because it removes an annoying
error condition that is hard to figure out for beginners.

Other than that I don't believe it is useful though: people that know
what empty() really does can use "!expr" when expr is not a variable,
which is less confusing, especially for strings.

Best,

>
> Nikita
>
> --
> PHP Internals - PHP Runtime Development Mailing List
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>



--=20
Etienne Kneuss
http://www.colder.ch