Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:70327
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 209.85.212.49 as permitted sender)
MIME-Version: 1.0
In-Reply-To: <1385221643.7200.25.camel@guybrush>
References: <CAHMUw2EmaofC=An8o=QrjnHAmdmtjprnCi69sRjMYcPDy37TDg@mail.gmail.com>
	<1385221643.7200.25.camel@guybrush>
Date: Sun, 24 Nov 2013 00:10:44 +0800
Message-ID: <CAHMUw2FjkecwbQyq9jb+3AtevL-BdU5y-tnn4XU4J56uqqY7Kw@mail.gmail.com>
To: =?ISO-8859-1?Q?Johannes_Schl=FCter?= <johannes@schlueters.de>
Cc: PHP Internals <internals@lists.php.net>
Content-Type: multipart/alternative; boundary=001a11c2ae767af6c604ebda5f03
Subject: Re: [PHP-DEV] Power function as operator
From: tjerk.meesters@gmail.com (Tjerk Meesters)

--001a11c2ae767af6c604ebda5f03
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

Hi Johannes,


On Sat, Nov 23, 2013 at 11:47 PM, Johannes Schl=C3=BCter
<johannes@schlueters.de>wrote:

> Hi,
>
> On Sat, 2013-11-23 at 00:58 +0800, Tjerk Meesters wrote:
> > It introduces the pow() function as an operator ** (double asterisk), a=
s
> > can be found in languages such as Python (with perhaps the notable
> > difference that it's right associative there).
>
> As a comment: In my view we try to keep the language understandable even
> for people who aren't as deep into it as we are. There having power as
> function serves two purposes. For one it is a normal function and can
> easily identified as such with clear precedence etc. Secondly people can

stick it in their favorite search engine and can understand what it
> means. Searching for ** however isn't as trivial.
>

I agree with both comments; it's easy to forget the practicality of being
able to search on something you don't know, although I would hope that
people recognize it as an operator and go here:
http://php.net/manual/en/language.operators.arithmetic.php :)


> Is the power operation really that common so we have to have it as an
> operator and opcode? I don't know what the threshold is, but -/ might be
> a nice unary (square) root operator ;-)
>

Actually, I was going to suggest creating a Unicode token =E2=88=9A for tha=
t ;-)


>
> Looking at github search results
> https://github.com/search?l=3DPHP&p=3D1&q=3Dpow&source=3Dcc&type=3DCode
> I see quite a few search results but most of them duplication (pow.phpt
> from our test suite comes very often) and in others I inspected it
> didn't see to be critical code paths gaining much from performance in
> (in my personal opinion) loosing readability.
>
> Randomly picked example:
>      } elseif ($dec - pow(2,$i) >=3D 0) {
> vs.
>      } elseif ($dec - (2 ** $i) >=3D 0) {
>
> https://github.com/pkeane/exercises/blob/68b58fb11abfbe8301c202b94906a4ec=
7e041c10/binpal.php#L59
> I consider the former to be better to parse with my brain.
>

Actually the latter could read:

} elseif ($dec - 2 ** $i >=3D 0) {

I can't judge on that, because my opinion will obviously be biased :)


>
> And yes, I understand that there are cases where this will boost
> performance by quite a bit, but then we'd rather make strlen() an
> opcode. ;-)
>

Well, why don't we? :)


>
> johannes
>
>
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>


--=20
--
Tjerk

--001a11c2ae767af6c604ebda5f03--