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References: <fc.00870cc1051f613f00870cc1051f613f.51f6c07@csisd.org> 
	<fc.3b9aca00e801453100870cc1051f613f.51f8b40@csisd.org> <7F7F9F17-A755-428B-93A6-1E0AFA20DE50@csisd.org>
Date: Thu, 17 Sep 2009 10:09:52 +0100
Message-ID: <10845a340909170209s277d1291tdaff7c0fc0b13275@mail.gmail.com>
To: Chris Trahey <ctrahey@csisd.org>
Cc: Larry Garfield <larry@garfieldtech.com>, 
	"internals@lists.php.net" <internals@lists.php.net>
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Subject: Re: [PHP-DEV] reference caller object
From: rquadling@googlemail.com (Richard Quadling)

2009/9/17 Chris Trahey <ctrahey@csisd.org>:
> 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 determin=
e
> who is sending the message, in a uniform way (not left up to the consumer=
s
> 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> wrot=
e:
>
>> If the object needs to behave differently based on who called it, there'=
s
>> already a very easy way to do that:
>>
>> class A {
>> =C2=A0function foo() {
>> =C2=A0 $b =3D new B();
>> =C2=A0 $b->bar($this);
>> =C2=A0}
>> }
>>
>> class B {
>> =C2=A0function bar($caller) {
>> =C2=A0 if ($caller instance of A) {
>> =C2=A0 =C2=A0 =C2=A0// ..
>> =C2=A0 }
>> =C2=A0}
>> }
>>
>> That's also therefore much more self-documenting and easier to test
>> (because
>> you can simulate what gets passed in) than a magic keyword. =C2=A0I 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(){
>> > =C2=A0 =C2=A0 =C2=A0 $bt =3D debug_backtrace();
>> > =C2=A0 =C2=A0 =C2=A0 return $bt[2]['object'];
>> > }
>> > But of course, there is a lot of uneccessary processing with that call=
.
>> > Perhaps it could be implimented similar to "self" and "parent" (actual=
y
>> > more like "static") keywords.
>> >
>> > So you could do:
>> > public function registerMe() {
>> > =C2=A0 =C2=A0 =C2=A0 if( ! (caller instanceof 'my_interface')) throw n=
ew
>> > dev_execption();
>> > =C2=A0 =C2=A0 =C2=A0 if( ! ($this->authenticateMod(caller))) throw new
>> > admin_exception('module
>> > not active');
>> > =C2=A0 =C2=A0 =C2=A0 $this->loadedMods[caller->module_id()] =3D caller=
;
>> > =C2=A0 =C2=A0 =C2=A0 return caller->onLoad();
>> > }
>> >
>> > Chris Trahey
>> > Web Applications Developer
>> > Database Administrator
>> > CSISD [Technology]
>>
>> --
>> Larry Garfield
>> larry@garfieldtech.com
>>
>> --
>

Isn't this exactly what the backtrace is for?

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-----
Richard Quadling
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