Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:78369
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain pthreads.org from 209.85.212.169 cause and error)
Message-ID: <1414388245.2624.135.camel@localhost.localdomain>
To: Stas Malyshev <smalyshev@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
Date: Mon, 27 Oct 2014 05:37:25 +0000
In-Reply-To: <544DA1CD.9070109@php.net>
References: <544DA1CD.9070109@php.net>
Content-Type: text/plain; charset="UTF-8"
Mime-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: Re: [PHP-DEV] [RFC] Using objects as keys
From: pthreads@pthreads.org (Joe Watkins)

On Sun, 2014-10-26 at 18:37 -0700, Stas Malyshev wrote:
> Hi!
> 
> I would like to present to your attention an RFC about using object as keys:
> 
> https://wiki.php.net/rfc/objkey
> 
> It was discussed in the past on the list:
> http://marc.info/?t=141145969600001&r=1&w=2
> and I think it makes sense to propose a formal RFC for it. Both the text
> and the code in the patch includes bits done by myself and Joe Watkins.
> The patch does not cover 100% of cases but should work for most
> reasonable scenarios, if something is wrong or you have ideas how to
> make it better please tell.
> 
> The name __hash is not final, I am open to using __toKey instead or any
> reasonable alternative, we may also include a couple of options in the
> vote if that will be a point of disagreement.
> 
> Thanks,
> Stas
> 

Morning Stas,
	
	Nicely done.
	
	Whether SPL classes, or any other classes, should use the functionality
should be left to another discussion.

	I wonder if it might be feasible to try and define what the contract of
this method is, in the same kind of way as the Java docs do for
Object.hashCode ? We can't have the exact same contract perhaps, but it
might be useful to try to define it at this stage.

	It seems __toScalar might be a good name, this is what the method
actually does, the engine then coerces to a type suitable for use as a
key, but you can return a double.

	It might be more forward thinking therefore to use the name __toScalar,
while today we'd only be using it for this, if we come up against the
requirement to treat an object as a scalar for anything else, we have
the machinery already and we don't have to add another magic method at
that time.

	Not sure what others think about that ... I liked the name __hash
better than __toKey, I like __toScalar better than those because it
describes what the method is meant to do the best.

Cheers
Joe