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Date: Wed, 2 Jun 2004 01:45:34 +0200
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Subject: Re: [PHP-DEV] delete in PHP
From: fschaper@intux.org ("Florian Schaper")

Timm Friebe wrote:
[...]
> In comparison to the proposed "delete", unset() only decreases the
> refcount.
>
> Have a look at the following examples:
>
> $ php-dev -r 'class Object { function __destruct() { echo
> "Destroyed\n"; }} $o= new Object(); unset($o); echo "Shutting
> down\n";'
> Destroyed
> Shutting down
>
> $ php-dev -r 'class Object { function __destruct() { echo
> "Destroyed\n"; }} $o= new Object(); $o2= $o; unset($o); echo
> "Shutting down\n";' Shutting down
> Destroyed
>
> In the second example, the destructor is not called until *after*
> shutdown. This is the small but noticeable difference between what
> Florian wants and what we currently provide.
>
> While I agree this could be interesting, I'm opposed to a keyword
> named "delete". Keywords may not be used as regular method names and
> a new keyword "delete" would add more BC breaks for people using
> methods called delete(). This:
>
>   class DBConnection {
>     function insert() { }
>     function update() { }
>     function select() { }
>     function delete() { }
>   }
>
> is an example which can be seen in numerous applications.
>

I really dont't want to warm up an discussion that has already been dealt
with,
but from my pov. - while I agree one should keep them to a minimum - minor
changes are
to be excpected in a major jump in version numbers and I'm sure this is not
unprecedented. Then again I don't get the eMails from the developers
going on about their broken code and I wouldn't want to volunteer for that.

For completeness:
Proposed behaviour of delete as opposed to unset:
 $ php-dev -r 'class Object { function __destruct() { echo
 "Destroyed\n"; }} $o= new Object(); $o2= &$o; delete $o; var_export( $o );
var_export( $o2 ); echo
 "Shutting down\n";' Destroyed NULL NULL Shutting down

> Then again, why doesn't unset() do this? That seems kind of
> inconsistent with the object-handle-pass-by-value semantics we have
> in PHP5.
>
> For the time being, using reference operators and setting the instance
> to NULL gives you a workaround:
>
> $ php-dev -r 'class Object { function __destruct() { echo
> "Destroyed\n"; }} $o= new Object(); $o2= &$o; $o= NULL; echo
> "Shutting down\n";' Destroyed
> Shutting down
>
> Interesting enough (from a user's pov, not the Engine's), unset() will
> not do the job:
>
> $ php-dev -r 'class Object { function __destruct() { echo
> "Destroyed\n"; }} $o= new Object(); $o2= &$o; unset($o); echo
> "Shutting down\n";' Shutting down
> Destroyed

I for one could manage without a delete keyword with unset destroying
the object referenced - which looks for me a more consistent
behaviour as Timm pointed out.

./regards

Florian