Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:78371
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: unknown (pb1.pair.com: domain php.net does not designate 66.111.4.25 as permitted sender)
Content-Type: text/plain; charset=utf-8
Mime-Version: 1.0 (Mac OS X Mail 8.0 \(1990.1\))
In-Reply-To: <544DE7FF.6030809@gmail.com>
Date: Mon, 27 Oct 2014 01:49:17 -0500
Cc: Joe Watkins <pthreads@pthreads.org>,
 PHP Internals <internals@lists.php.net>
Content-Transfer-Encoding: quoted-printable
Message-ID: <BC9CC8C6-366F-4537-8B7F-38C14BE7B0D8@php.net>
References: <544DA1CD.9070109@php.net> <1414388245.2624.135.camel@localhost.localdomain> <544DE7FF.6030809@gmail.com>
To: Stas Malyshev <smalyshev@gmail.com>
Subject: Re: [PHP-DEV] [RFC] Using objects as keys
From: willfitch@php.net (Will Fitch)


> On Oct 27, 2014, at 1:36 AM, Stas Malyshev <smalyshev@gmail.com> =
wrote:
>=20
> Hi!
>=20
>> 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,=20
> __toScalar does not express the fact why we are calling it - to use it
> as a key. It's not just a scalar conversion, it's conversion for the
> purpose of hashing.

I think that=E2=80=99s the general confusion around this. Generally, the =
examples provided (Java/Ruby/Python) are based on two things:

1. The value returned is a signed 32-bit (debatable) integer
2. Each hash is calculated based on the properties available (and =
assigned).=20

With this in mind, should we not expect, at the very least, and integer =
on each return?  For example:

class Company
{
    private $companyId;
    private $clientId;

    public function __construct($companyId, $clientId)
    {
        $this->companyId =3D (int) $companyId;
        $this->clientId =3D (int) $clientId;
    }

    public function __toHash()
    {
        return $this->companyId * $this->clientId;
    }
}

This is a trivial example, it can be used to define a simple approach =
for object =E2=80=9Cuniqueness=E2=80=9D and prevent potentially prevent =
duplicate hashes in a structure.

That said, with PHP=E2=80=99s typeless approach, I understand the case =
could be made for combining values into a string.  To me, it seems more =
logical and uniform to require an integer - whether signed or unsigned.

>=20
>=20
> --=20
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>=20