Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:50755
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: error (pb1.pair.com: domain stefan-marr.de from 85.88.12.247 cause and error)
Mime-Version: 1.0 (Apple Message framework v1082)
Content-Type: text/plain; charset=windows-1252
In-Reply-To: <1faa4c3db62771335db714507ac2adfa.squirrel@webmail.basnetworks.net>
Date: Wed, 1 Dec 2010 08:59:18 +0100
Cc: "Stas Malyshev" <smalyshev@sugarcrm.com>,
 "internals@lists.php.net" <internals@lists.php.net>
Content-Transfer-Encoding: quoted-printable
Message-ID: <6EC3583E-E7B7-431D-B544-82135A33E351@stefan-marr.de>
References: <ae7aa0536c47a2ac725222d49918183f.squirrel@webmail.basnetworks.net> <003601cb8fd0$f6494e80$e2dbeb80$@com> <4CF3B855.5010406@sugarcrm.com> <003401cb8fee$1be39840$53aac8c0$@com> <2450924ae03481f5b1382a7f00e5743d.squirrel@webmail.basnetworks.net> <4CF50245.5020807@sugarcrm.com> <ed0a2b6089e32bc3def3c14a1f510246.squirrel@webmail.basnetworks.net> <4CF5118B.2030300@sugarcrm.com> <1faa4c3db62771335db714507ac2adfa.squirrel@webmail.basnetworks.net>
To: president@basnetworks.net
Subject: Re: [PHP-DEV] RFC: C-sharp style property get/set syntax for PHP
From: php@stefan-marr.de (Stefan Marr)

Hi:

On 01 Dec 2010, at 01:31, president@basnetworks.net wrote:

>>> That is true for PHP variables.  isset is basically saying "does =
this
>>> variable exist", and unset is saying to get rid of it.
>>=20
>> This is also true for object properties - see magic methods. I don't =
see
>> why you shouldn't be able to unset them - you can do that with =
regular
>> properties... So what you imagine would happen if you call
>> unset($foo->property) or isset($foo->property)?
>=20
> Its not a matter of consistency - Properties, as a cross-language =
concept
> are not meant to work that way. =20
I tend to disagree.
The need to be consistent inside of PHP has precedence over being =
consistent with other languages.


> You need to think of a property as a set
> of two methods that just have a pretty syntax.  Methods cannot be =
unset,
> and nor should properties be allowed to.  isset() should simply tell =
us
> whether a property with the specified name is part of the class or =
not.
I think, it really is the other way around.
Properties are meant to give the programmer the illusion that she is =
just having a field.
That is abstraction. She does not care about implementation details.
And that is the power of properties.

isset() and unset() are perfectly fine in that context.
And I do not see a problem to provide the standard semantics for them =
automatically, and let the programmer add isset/unset methods to the =
property as needed in exactly the same style as get/set.

There is a good usecase for asking whether a property has been set, for =
instance to verify initialization.
And, of course unset has also a useful meaning. It is about the value, =
and even so there are methods around a value, properties are meant to be =
values.
There are definitely use-cases where that does not hold, but that is =
application specific.


> isset() in the way you suggest would just be confusing.  It would =
allow is
> to say that a property does not exist, when in fact it does exist.  =
This
> is not logical.
=46rom the docu: isset =97 Determine if a variable is set and is not =
NULL
There is nothing confusing about isset($this->Hours) =3D=3D FALSE in =
your example if isset($this->seconds) =3D=3D FALSE.

Best regards
Stefan

--=20
Stefan Marr
Software Languages Lab
Vrije Universiteit Brussel
Pleinlaan 2 / B-1050 Brussels / Belgium
http://soft.vub.ac.be/~smarr
Phone: +32 2 629 2974
Fax:   +32 2 629 3525