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Date: Fri, 19 Jul 2013 22:46:22 -0700
Message-ID: <CADajX4DO-MgwZkrJBz1zp-o_kJyHpQ+GPJAWZ=9i2_wSpwc+sA@mail.gmail.com>
To: PHP internals <internals@lists.php.net>
Cc: Sherif Ramadan <theanomaly.is@gmail.com>, Yasuo Ohgaki <yohgaki@ohgaki.net>, 
	Sara Golemon <pollita@php.net>
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Subject: Re: [PHP-DEV] Operator precedence is undefined?
From: aharvey@php.net (Adam Harvey)

(Piggy-backing on Sara's e-mail, although this is more a response to
Sherif and Yasuo.)

On 19 July 2013 22:33, Sara Golemon <pollita@php.net> wrote:
> I never said that the compiler might magically produce differing results
> for the same input.  I said that the language's definition does not decla=
re
> a defined behavior for such expressions with combined side effects.

This is also a classic piece of undefined behaviour in most C-like
languages =E2=80=94 Bjarne Stroustrup lists it in his C++ FAQ, for instance=
:
http://www.stroustrup.com/bs_faq2.html#evaluation-order. That's not to
say that PHP necessarily has to be the same as other languages in its
"family" (nested ternaries, anyone?), but I don't think that PHP is
really doing anything different here that would make it well defined:
AFAIK, the only places PHP makes guarantees about the order of
evaluation with regard to binary operators is short circuiting the
boolean operators.

> As to reverting commits.  When the initial commit was made in haste durin=
g
> an active discussion, a revert is entirely appropriate and has nothing to
> do with placing one's opinion over another's.  It has to do with placing
> the process of consensus building over unilateral cowboy commits.

+1.

Adam