Re: public readonly variables

[Adam Richardson <simpleshot@xxxxxxxxx>]

On Fri, Apr 23, 2010 at 6:19 AM, Richard Quadling
<rquadling@xxxxxxxxxxxxxx>wrote:

> On 23 April 2010 10:55, Ashley Sheridan <ash@xxxxxxxxxxxxxxxxxxxx> wrote:
> > I know the subject line might sound a bit like an oxymoron, but bear
> > with me!
> >
> > What I'd like to have is a property of an object that behaves like a
> > public variable when it comes to reading, but like a protected one when
> > it comes to writing, as it would make my code a lot easier to read.
> >
> > I know about the __get($var) method to magically provide this behaviour,
> > but from all I've read it can be pretty slow compared to a regular
> > public variable. I've seen a thread on the dev lists where someone
> > requested it, but can't find anything in the manual.
> >
> > Does anyone know if this is available in a later version of PHP, or if
> > it's implementation is penned for some time in the future?
> >
> > Thanks,
> > Ash
> > http://www.ashleysheridan.co.uk
> >
> >
> >
>
> What you are asking for is commonly known as accessibility. This has
> been discussed on the list and is something I think would be a great
> feature.
>
> http://wiki.php.net/rfc/propertygetsetsyntax is an incomplete RFC (it
> says it is incomplete at the top).
>
> The last update was 2010/01/08 22:11, so a few months old.
>
> Hopefully, some of the clever brains here can get to grips with it and
> come to some consensus.
>
>
> Whilst you can easily code __get()/__set() or getVar()/setVar()
> methods to deal with it, with the later ones being significantly
> easier to docblock, there is no easy way to document the property,
> only the methods to set or get the property.
>
>
> Richard.
>
>
>
>
>
>
> --
> -----
> Richard Quadling
> "Standing on the shoulders of some very clever giants!"
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>
I've sometimes implemented a scheme where I create the variable, then unset
it in the constructor and rely on the magic method.  I know you were
concerned about the performance of magic methods, and I don't have a
solution for that :(

For example:

<?php
/**
 * Description of PHPClass that documents nicely and still protects
variables from reassignment.
 *
 * @author Adam Richardson
 */
class PHPClass {
    /**
     * Name for object.
     * @var String
     */
    public $name;
    /**
     * Size of something really important.
     * @var int
     */
    public $size;
    /**
     * Local storage of magic vars
     * @var array
     */
    private $_vars = array();
    /**
     * Create object and initialize instance vars.
     * @param array $instance_vars
     */
    function __construct(array $instance_vars)
    {
        unset($this->name);
        unset($this->size);

        $this->_vars = $instance_vars;
    }
    function __get($name)
    {
        return $this->_vars[$name];
    }
}

$obj = new PHPClass($instance_vars = array('name' => 'Billy', 'size' =>
1000));

echo $obj->name;

?>

Adam

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