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Date: Mon, 16 Jul 2012 08:59:12 -0400
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To: Ferenc Kovacs <tyra3l@gmail.com>
Cc: PHP Internals <internals@lists.php.net>
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Subject: Re: [PHP-DEV] supporting the final keyword for properties
From: ircmaxell@gmail.com (Anthony Ferrara)

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Ferenc,

On Mon, Jul 16, 2012 at 8:25 AM, Ferenc Kovacs <tyra3l@gmail.com> wrote:

> Hi,
>
> The recent
> http://www.mail-archive.com/internals@lists.php.net/msg59301.html
> discussion
> made me wonder why did we decide not supporting the final keywords for
> properties as it would provide an easy way for read-only attributes (const
> would be a better choice in performance wise, but then you can only set it
> in your declaration where no dynamic expression is allowed.)
>
> I would like it to work the same way as it does in java(
> http://docs.oracle.com/javase/specs/jls/se7/html/jls-4.html#jls-4.12.4)
> eg.
> you can set the initial value either in the declaration or later on, but
> after it is set, you can't change it, trying to do that would create a
> recoverable fatal error (or throwing an exception which extends
> RuntimeException).
>
> What do you think? Would this be viable? Is there any still-present reason
> why we shouldn't support that?
>

My question would be where in code would this be enforced? A trivial
implementation could be done in the object.write_property handler. But
wouldn't things like references and the such (read_property and
get_property_ptr_ptr, as well as get_properties) also be paths to
writability?

Would that then mean that this would need to be added to the zval type
directly, and not just the property table? And if that's the case, why not
make it final for the entire engine (meaning that I can declare a global
property as final using `final $var = 1;`)... Thereby making this a rather
significant engine changes? Or is there an easier way that I'm missing...?

Anthony

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