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Date: Wed, 28 May 2008 09:05:56 +0300
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Subject: Re: [PHP-DEV] RFC: allow_call_pass_by_reference
From: sv_forums@fmethod.com ("Stan Vassilev | FM")


Hi,

There are three purposes:

1) At call time, nothing significes what is the caller passing, the syntax 
is the same for passing reference or passing value, so it's prone to 
confusion. You're passing something which *may* or *may not* be modified if 
taken as a reference. Quick, is the variable taken by reference here 
somefunction($hi).  A more clear version of the syntax is what I covered in 
my original email, where declaring function foo(& $foo) is a sort of 
contract that *forces* (with error) that the variable is passed by reference 
at call time, thus making the actions of the function explicit.

2) There's a broken symmetry here. While passing by reference is implicit at 
call time, at return time it's not. I need to both declare the function 
return by reference AND use "= & " to assign the results. Otherwise I get a 
copy. That's a problem I often have. There's no compiler error to warn me I 
did otherwise.

I'd rather all those be explicit( require pass/return by val, require 
pass/return by refr: "&", accepts both "&?"), and the strict cases throw 
errors when the contract is not met at both sides.

3) As I mentioned there are three use cases, of which we support two, which 
I covered in my original email.

The reason I said "in a perfect world" is because the current "hidden" pass 
by reference at call time will be incompatible with that scheme, so I doubt 
anyone would consider it.

Regards,
Stan Vassilev

> Hi!
>
>> In a perfect world, here's how I'd do it, of course the actual syntax can 
>> be something else (this also improves the understanding of the code as it 
>> makes the intent explicit, versus implicit at call time, as it is now):
>>
>> ---
>>
>> function foo(& $a) {} // allows only explicit pass by reference
>>
>> foo($a); // illegal, error
>> foo(& $a); // legal, pass by reference
>
> I'm not sure I understand what's the purpose of this. Passing by reference 
> means that function may modify it's parameter. I see no reason why such 
> function should be called with some special syntax, could you explain?
> -- 
> Stanislav Malyshev, Zend Software Architect
> stas@zend.com   http://www.zend.com/
> (408)253-8829   MSN: stas@zend.com
>
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