Newsgroups: php.internals
Path: news.php.net
Xref: news.php.net php.internals:48186
Mailing-List: contact internals-help@lists.php.net; run by ezmlm
Received-SPF: pass (pb1.pair.com: domain easyflirt.com designates 91.199.255.56 as permitted sender)
Message-ID: <4BDFCBA4.1030700@easyflirt.com>
Date: Tue, 04 May 2010 09:24:20 +0200
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.1.9) Gecko/20100423 Thunderbird/3.0.4
MIME-Version: 1.0
To: internals@lists.php.net
References: <4BDEC91F.9080305@easyflirt.com> <4BDEEEDA.1050806@cschneid.com> <k2jb9defe2f1005031434r120154f1y9f7b6a93118178c3@mail.gmail.com>
In-Reply-To: <k2jb9defe2f1005031434r120154f1y9f7b6a93118178c3@mail.gmail.com>
Content-Type: multipart/alternative;
 boundary="------------030800090008060205080202"
Subject: Re: [PHP-DEV] Re: Closure local return
From: mathieu.suen@easyflirt.com ("mathieu.suen")

--------------030800090008060205080202
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit

On 05/03/2010 11:34 PM, Tjerk Anne Meesters wrote:
> On Mon, May 3, 2010 at 11:42 PM, Christian Schneider
> <cschneid@cschneid.com>  wrote:
>    
>> mathieu.suen wrote:
>>      
>>> May be it could be interesting to have a syntax for returning from the
>>> define scope.
>>> For example.
>>>
>>> $findedElment = $myList->selectIfAbsent($fooo, function(){
>>>      return 'No item founded'; //Retrun from the define scope
>>> })
>>> //Do somthing with $findedElment
>>>        
>> I think you actually misunderstand the difference in
>> http://en.wikipedia.org/wiki/Closure_%28computer_science%29#Differences_in_semantics
>>
>> The way I read if the difference is wether it returns from the closure
>> function or the surrounding function *calling* it. Not the *defining* scope.
>>      
> Mathieu is right in that it would return from the defining scope, but
> it's important to note that when the closure is called the function
> that defined the closure is still on the stack.
>
> Consider the following example:
>
> function f() { return function() { return; } }
> $c = f();
> $c();
>
> If the semantics of Smalltalk were to apply, this would give an error,
> because it's impossible to return from f() when the closure is being
> called.
>
>    
>> And no, it doesn't make sense in the PHP context IMHO.
>>      
> I second that ;-) In terms of clarity I find that the ECMAScript
> implementation is much clearer.
>
>    

Of course ECMAScript has the same semantic than PHP. :)
(for this particular point, I don't mean for the rest)
May be one could fink of a different syntax:

function() { return-from-def-scope; }

And that would also remove the ambiguity in your example:

function f() { return function() { return-from-def-scope; } }




>> - Chris
>>
>> --
>> PHP Internals - PHP Runtime Development Mailing List
>> To unsubscribe, visit: http://www.php.net/unsub.php
>>
>>
>>      
>
>
>    

-- Mathieu Suen
	


--------------030800090008060205080202--