Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:46676
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain gmail.com designates 72.14.220.159 as permitted sender)
DomainKey-Status: bad
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=gmail.com; s=gamma;
        h=mime-version:sender:in-reply-to:references:date
         :x-google-sender-auth:message-id:subject:from:to:cc:content-type
         :content-transfer-encoding;
        b=pvoTI9RcpcBHS+lDvr4fi35yk1yyMEJuJAcDaIu3vvfExmL8beGeW3jK+rZJmHqp6L
         prdvFpL02c8zd0I7ul5d6b29BxJXIJhwbXyZrL98ENN7oV3ndzphbNRogpOACMoTOQca
         eeZGp4WEqobkU/CGrthM0dNXFZ2GiNBrole0s=
MIME-Version: 1.0
Sender: ekneuss@gmail.com
In-Reply-To: <e2e02fe1001121440l4c893a3chfd67c0173f567d56@mail.gmail.com>
References: <BF.85.26332.88E6B4B4@pb1.pair.com>
	 <e666c3891001111729n7294ef23la55b02272044662e@mail.gmail.com>
	 <3A.94.26332.3E9EB4B4@pb1.pair.com>
	 <c25f8d341001111932o3a0f28e8w27985700c6684454@mail.gmail.com>
	 <e2e02fe1001121440l4c893a3chfd67c0173f567d56@mail.gmail.com>
Date: Wed, 13 Jan 2010 11:12:05 +0100
Message-ID: <e666c3891001130212y2cd4102eq4eab9f9ea2994b51@mail.gmail.com>
To: Chris Stockton <chrisstocktonaz@gmail.com>
Cc: mm w <0xcafefeed@gmail.com>, internals@lists.php.net
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Subject: Re: [PHP-DEV] __toString(), __toArray()
From: webmaster@colder.ch (Etienne Kneuss)

Hello,

On Tue, Jan 12, 2010 at 11:40 PM, Chris Stockton
<chrisstocktonaz@gmail.com> wrote:
> Hello,
>
> On Mon, Jan 11, 2010 at 8:32 PM, mm w <0xcafefeed@gmail.com> wrote:
>> cast is not needed in PHP
>>
>> i 'd rather be more interesting in
>>
>> class Obj {
>> =A0 =A0 function __catch($data, $type) {
>> =A0 =A0 =A0 =A0 =A0 =A0//$type [ static_method, method, get_property, se=
t_property]
>> =A0 =A0 =A0 =A0 =A0 =A0if (observed && =A0$type =3D=3D set_property && s=
omevalueIsObserved) {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$observer->notify("somevalue::valueWi=
llChanged");
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$this->somevalue =3D $data['somevalue=
'];
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0$observer->notify("somevalue::valueDi=
dChanged");
>> =A0 =A0 =A0 =A0 =A0 =A0} else {
>> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0continue__call();
>> =A0 =A0 =A0 =A0 =A0 =A0}
>> =A0 =A0 }
>> }
>
> What? ...
>
>>> Etienne Kneuss wrote:
>>> This is where operator over-loading would be useful however perhaps onl=
y
>>> explicit casts would make sense here.
>
> I beleive adding a __cast(string $type) would be a useful feature for
> me, very often I have a toArray method defined. I agree with you that
> due to unexpected edge cases with operator precedence and general type
> juggling that __cast should only be called on explicit (cast).
>
> I.E.:
> class Int { public function __cast($type) { return 'int' =3D=3D $type ? 1=
5 : 0; } }
> $r =3D new Int;

This is an exemple where __cast would be very wrong. At the very
least, it should return a value that is an inhabitant of the requested
type! Do you really want (bool)new Int() to be Int 0?

as a result, you have three solutions:
1) have the engine issue an error in case the return value is not compatibl=
e
2) provide a return value for every possible types requested
3) throw an exception in case the cast is not handled

In the end, it looks way more complicated/magic than _simply_ defining
a toArray method that is used whenever you need an object to be an
array. You need an explicit cast anyway, so it's (array)$obj vs
$obj->toArray().

>
> var_dump($r + 1); // 2
> var_dump((int) $r + 1); // 16
> var_dump((bool) $r + 1); // 1
>
> --
> PHP Internals - PHP Runtime Development Mailing List
> To unsubscribe, visit: http://www.php.net/unsub.php
>
>



--=20
Etienne Kneuss
http://www.colder.ch