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Date: Wed, 16 Sep 2009 22:01:13 -0500
Cc: "internals@lists.php.net" <internals@lists.php.net>
Subject: Re: [PHP-DEV] reference caller object
From: ctrahey@csisd.org (Chris Trahey)

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It seems worthwhile in a service-provider situation where you do not  
wish to enforce use of $this in service consumers.
The service provider can impliment caller without modifying existing  
code.

Semantically, it should be considered redundant to pass $this in a  
method call. There should be an implicit way for a message recipient  
to determine who is sending the message, in a uniform way (not left up  
to the consumers of your API to impliment).

Thanks for your consideration.

Chris Trahey
Sent from my iPhone

On Sep 16, 2009, at 8:47 PM, Larry Garfield <larry@garfieldtech.com>  
wrote:

> If the object needs to behave differently based on who called it,  
> there's
> already a very easy way to do that:
>
> class A {
>  function foo() {
>    $b = new B();
>    $b->bar($this);
>  }
> }
>
> class B {
>  function bar($caller) {
>    if ($caller instance of A) {
>       // ..
>    }
>  }
> }
>
> That's also therefore much more self-documenting and easier to test  
> (because
> you can simulate what gets passed in) than a magic keyword.  I don't  
> see a
> need for new magic constants here.
>
> On Wednesday 16 September 2009 3:59:16 pm Chris Trahey wrote:
> > (Please direct me elsewhere if necessary, this is a feature request)
> >
> > It would be handy to allow a method to behave differently based on  
> who is
> > calling it.
> > the function I am looking for would essentially do this:
> >
> > function getCaller(){
> >       $bt = debug_backtrace();
> >       return $bt[2]['object'];
> > }
> > But of course, there is a lot of uneccessary processing with that  
> call.
> > Perhaps it could be implimented similar to "self" and  
> "parent" (actualy
> > more like "static") keywords.
> >
> > So you could do:
> > public function registerMe() {
> >       if( ! (caller instanceof 'my_interface')) throw new  
> dev_execption();
> >       if( ! ($this->authenticateMod(caller))) throw new  
> admin_exception('module
> > not active');
> >       $this->loadedMods[caller->module_id()] = caller;
> >       return caller->onLoad();
> > }
> >
> > Chris Trahey
> > Web Applications Developer
> > Database Administrator
> > CSISD [Technology]
>
> --
> Larry Garfield
> larry@garfieldtech.com
>
> --

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