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To: Rasmus Schultz <rasmus@mindplay.dk>, "internals@lists.php.net"
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Thread-Topic: [PHP-DEV] [RFC] Propety Accessors v1.1
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Date: Thu, 11 Oct 2012 00:06:16 +0000
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Subject: RE: [PHP-DEV] [RFC] Propety Accessors v1.1
From: cpriest@zerocue.com (Clint Priest)

Jazzer's example was extending an accessor and her statement about no way t=
o stop the developer from doing what she did there without read-only is cor=
rect.

There are other, more verbose and less simple ways to accomplish read-only =
and write-only (preventing sub-classes from defining a getter, etc, namely =
through the use of final) but none of them are as simple and easily readabl=
e as public read-only $hours { ... }



> -----Original Message-----
> From: Rasmus Schultz [mailto:rasmus@mindplay.dk]
> Sent: Wednesday, October 10, 2012 6:47 PM
> To: internals@lists.php.net
> Subject: Re: [PHP-DEV] [RFC] Propety Accessors v1.1
>=20
> > There's no way to stop the developer from doing that without read-only.
>=20
> Yes, there is - I don't even know why would write it that way - doesn't s=
eem to make much sense.
>=20
> What you probably should be doing, is this:
>=20
> class A {
>   private $seconds =3D 3600;
>=20
>   public $hours {
>     get() { return $this->seconds / 3600 };
>   }
>  }
>=20
> Keep your field private - now try extending this with a write-accessor.
>=20
> I think that read-only is really almost merely a "pseudonym" for "read-on=
ly accessor for a private field" - what you're really trying to
> do, is protect the field behind the accessor, not the accessor itself.
>=20
> In the same way, write-only is practically synonymous with "write-only ac=
cessor for a private field" - to some extend (at least) the
> point of having accessors to begin with, is to protect the underlying val=
ue(s) from unauthorized or incorrect use.
>=20
> You can relax your read-only or write-only accessors by declaring the bac=
king field(s) protected - this would be the equivalent of
> declaring a read-only accessor that you are permitted to extend with a wr=
ite-accessor if you need to...
>=20
>=20
> ---------- Forwarded message ----------
> From: Jazzer Dane <tbprogrammer@gmail.com>
> To: Leigh <leight@gmail.com>
> Cc: Clint Priest <cpriest@zerocue.com>, "internals@lists.php.net" < inter=
nals@lists.php.net>
> Date: Tue, 9 Oct 2012 19:33:20 -0700
> Subject: Re: [PHP-DEV] [RFC] Propety Accessors v1.1
>=20
> > class A {
> > >   public $seconds =3D 3600;
> > >
> > >   public $hours {
> > >     get() { return $this->seconds / 3600 };
> > >   }
> > > }
> > >
> > > class B extends A {
> > >   public $hours { // Maintains 'get' from class A
> > >     set($value) { $this->seconds =3D $value; }
> > >   }
> > > }
> > >
> > ^There's no way to stop the developer from doing that without read-only=
.