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Date: Thu, 19 Sep 2013 10:10:23 +0100
Message-ID: <CAPwsocGJ5=1Loks3NDUt6Pd-o089c5JRvqwRFTzPGgPn4gkFGw@mail.gmail.com>
To: William Bartlett <william.a.bartlett@gmail.com>
Cc: Bob Weinand <bobwei9@hotmail.com>, 
	Developers List PHP Mailing <internals@lists.php.net>
Content-Type: text/plain; charset=ISO-8859-1
Subject: Re: [PHP-DEV] Re: Allowing is_* functions to accept multiple parameters
From: leight@gmail.com (Leigh)

On 19 September 2013 03:20, William Bartlett
<william.a.bartlett@gmail.com> wrote:
> I would argue that LTR support is also inconsistent / not desired.
>
> If I wrote:
>
> $i = 0;
> is_three($i = $i + 1, $i = $i + 1, $i = $i + 1);
>
> I would certainly expect is_three to return false, but I would also expect
> $i to contain three.  php doesn't normally evaluate arguments lazily, it
> would be weird for that behavior to suddenly crop up.  users who want lazy
> evaluation can write it the traditional way (with &&).

I think there has been some misunderstanding of my intention here
(maybe I communicated it badly) - Originally I was pretty confused
when reading Bobs response as it was way beyond the scope of what I
was proposing.

When I say parameters evaluated LTR / boolean short-curcuit evaluation
I mean it like this:

$i = 1;
$f = 1.1;

is_int($i, $f, $i, $i) => is_int(1) && is_int(1.1) && is_int(1) && is_int(1)

is_int($i++, $f++, $i++, $i++) =>  is_int(1) && is_int(1.1) &&
is_int(2) && is_int(3)

$i == 4;
$f == 2.1;

Internally, processing will stop at the is_int(1.1) and not bother
continuing to check the types of further arguments.

I did not mean:

is_int($i++, $f++, $i++, $i++) => is_int($i++) && is_int($f++) &&
is_int($i++) && is_int($i++)

As Bob said, this would take some pretty nuts opcode processing, and
is completely not worth the effort involved. I may have emphasised a
parallel with isset() a bit too much, however isset() cannot take
expressions as input.

I was never intending to try and evaluate parameters as they were
passed and jump over subsequent evaluations. Standard function call
semantics would still apply. I hope that people find that less
confusing / unexpected.