Hi.
Personally, I beleive that (A) approach is the best: "bind $this to
the object scope at creation" and never change it, issue error when
$this is used where not available. It also seems to me like this way
it could be implemented with better performance, am I right?
Dynamically changing $this introduces confusion. You can use
$this->foo or $this->bar() inside a closure, but when $this
dynamically changes - you cannot be sure that "foo" property or "bar"
method is still there. Furthermore, dynamic approach introduces even
more mess when thinking about availability of private/protected class
members.
Consider this code:
class Foo {
private $closure;
function __construct()
{
/* It seems natural to me that, doing this assignment from within the class,
one can use private members inside the closure */
$this->closure = function() { $this->privateMethod(); };
}
function setClosure($closure)
{
$this->closure = $closure;
}
function getClosure()
{
return $this->closure;
}
}
$foo = new Foo();
$foo->getClosure()->__invoke();// #CALL-1
$foo->setClosure(function() {
/*
But is it good to use private members here? It seems like it would
break encapsulation,
and the information that the class was designed to hide - is now
made available in public access,
although indirect.
*/
$this->privateMethod();
});
$foo->getClosure()->__invoke();// #CALL-2
In the end, I would like PHP to issue error when $this is used in
#CALL-2 but to continue working on #CALL-1.
The (A) approach seems to me more predictable, more simple, it has
less information the developer needs to keep in mind when using
closures.
2009/11/17 Mathieu Suen <mathieu.s...@easyflirt.com>:
> Chris Stockton a écrit :
>>
>> Hello,
>>
>> On Tue, Nov 17, 2009 at 2:59 AM, Mathieu Suen
>> <mathieu.s...@easyflirt.com> wrote:
>>>
>>> Christian Seiler a écrit :
>>>>
>>>> Hi,
>>>>
>>>> since a few months have passed since the last discussion on this topic
>>>> and perhaps people had time to gather some experience with the current
>>>> closure implementation in PHP 5.3 I'd like to restart the debate on
>>>> $this in closures and object extension.
>>
>> I believe that (D) wins my vote, and it convinces me twice. Once
>> because I believe it is the most intuitive for users (A), and twice
>> because I believe it is also the most useful (C) for users. In my
>> opinion It seems the most "PHP" way.
>>
>> -Chris
>>
>
> (D) is quite inconstant:
>
> $block = $foo->closur;
>
> $foo->closur();
> $block();
>
> This would produce 2 different output.
> For (C) here is my objection:
>
> Suppose that we are in a MVC pattern.
> In a controller on could do:
>
> $model->onFailDo(function () {$this->reportError()});
> $model->save();
>
>
> In the model side:
>
> public function onFailDo($block)
> {
> $this->signalFailure = $block
> }
>
> public function save()
> {
> //... Something wrong happen
> return $this->signalFailure();
> }
>
> If you dynamically bind the $this you are obliged to treat the error
> reporting in the model which is not a good idea. Even worst you can't even
> catch up the error in the controller.
> It also mean that the closure is getting tightly coupled with anyone who is
> using it. And passing closure to different object is like spreading
> dependency over all the system.
>
> -- Mathieu Suen
>
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>
>
--
Regards,
Victor
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