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To: "Sara Golemon" <pollita@php.net>, "Pierre Joye" <pierre.php@gmail.com>
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Date: Sat, 21 Jul 2012 14:11:18 +0200
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Subject: Re: [PHP-DEV] zend_parse_parameters() improvements
From: glopes@nebm.ist.utl.pt ("Gustavo Lopes")

Em Sat, 21 Jul 2012 13:13:23 +0200, Pierre Joye <pierre.php@gmail.com>  
escreveu:

> On Fri, Jul 20, 2012 at 12:20 AM, Sara Golemon <pollita@php.net> wrote:
>> Okay, well... the main pieces of feedback I'd give on it then is to not
>> change the behavior of the '!' modifier.  That's bad BC.
>
> Fully agreed, if we can avoid the introduction of yet another set of
> #ifdef, then I'm all for it.
>
>>  Rather, introduce
>> a new modifier for checking if a parameter was passed.  Secondly, make
>> these two separate patches as the new modifier is a separate feature  
>> from the single-arg parameter parsing.
>
> Agreed here too.
>

In the interest of a meaningful discussion, please read the proposal and  
the rest of the thread (or at least the other responses to the message you  
were replying to).

To reiterate: this proposal has nothing with Stas' proposal and  
passed/unpassed/default parameters except insofar as it would alleviate  
the need for having a mechanism to detect whether a parameter was skipped.  
One argument raised against skipparams was 'use NULL instead'. Ignoring  
the fact that many functions have non-NULL default parameters, this is  
difficult to do with non-string scalars in internal functions, which under  
my proposal would no longer be the case.

In any case, my proposal is not at odds with Stas'. If you think 'default'  
is useful in userland (where the problems the proposed changes address do  
not exist), you will still find Stas' proposal compelling.

It is not redundant either. You may want to use null-or-scalar in  
mandatory arguments. And if you want a skippable non-string scalar  
argument in an internal function, you will nevertheless probably want to  
assign it a default value (otherwise you'd have something without a  
parallel in user-space -- a skippable argument without a default value),  
and  NULL will be the logical choice in many cases. Any wrapper in  
userspace would look weird if you relied exclusively on skipparams.  
Instead of:

function userland_wrapper($a, $b=null) {
     return internal_func(2*$1, $b === null ? null : 2 * $b);
}

you would need:

function userland_wrapper($a, $b=null) {
     $args = func_get_args();
     $args[0] *= 2;
     if (isset($args[1])) {
         $args[1] *= 2;
     } else {
         unset($args[1]);
     }
     call_user_func_array('internal_func', $args);
}

-- 
Gustavo Lopes