[RFC] Propety Accessors v1.1

Jazzer's example was extending an accessor and her statement about no way to stop the developer from doing what she did there without read-only is correct.

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 readable 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

There's no way to stop the developer from doing that without read-only.

Yes, there is - I don't even know why would write it that way - doesn't seem to make much sense.

What you probably should be doing, is this:

class A {
private $seconds = 3600;

public $hours {
get() { return $this->seconds / 3600 };
}
}

Keep your field private - now try extending this with a write-accessor.

I think that read-only is really almost merely a "pseudonym" for "read-only accessor for a private field" - what you're really trying to
do, is protect the field behind the accessor, not the accessor itself.

In the same way, write-only is practically synonymous with "write-only accessor for a private field" - to some extend (at least) the
point of having accessors to begin with, is to protect the underlying value(s) from unauthorized or incorrect use.

You can relax your read-only or write-only accessors by declaring the backing field(s) protected - this would be the equivalent of
declaring a read-only accessor that you are permitted to extend with a write-accessor if you need to...

---------- Forwarded message ----------
From: Jazzer Dane tbprogrammer@gmail.com
To: Leigh leight@gmail.com
Cc: Clint Priest cpriest@zerocue.com, "internals@lists.php.net" < internals@lists.php.net>
Date: Tue, 9 Oct 2012 19:33:20 -0700
Subject: Re: [PHP-DEV] [RFC] Propety Accessors v1.1

class A {

public $seconds = 3600;

public $hours {
get() { return $this->seconds / 3600 };
}
}

class B extends A {
public $hours { // Maintains 'get' from class A
set($value) { $this->seconds = $value; }
}
}

^There's no way to stop the developer from doing that without read-only.