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To: "Stas Malyshev" <smalyshev@sugarcrm.com>
Cc: "Nikita Popov" <nikita.ppv@gmail.com>, "Sara Golemon" <pollita@php.net>,
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Date: Fri, 20 Jul 2012 02:29:04 +0200
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Subject: Re: [PHP-DEV] zend_parse_parameters() improvements
From: glopes@nebm.ist.utl.pt ("Gustavo Lopes")

Em Fri, 20 Jul 2012 02:07:31 +0200, Stas Malyshev <smalyshev@sugarcrm.com>  
escreveu:

>> Default parameters and unpassed parameters enter the scene because it's
>> idiomatic to pass NULL to have the same effect as not passing that
>> parameter.
>
> Actually, as it never worked with int parameters, I'd not really call it
> idiomatic just yet.

OK I should have qualified my statement -- it's idiomatic in userland.

>
> I was just thinking - since we have basically no code relying on this,
> why introduce rather artificial concept of "null means no parameter"
> (which I'm sure won't work in all cases and won't be expected in all
> cases) if we can have perfectly good concept "default means no
> parameter" which won't clash with any existing code?
>
> Note that this still will require something like l! - I'm actually
> working right now on finding all the places we have something like this
> for my default params patch - so I agree with that part of the argument.
> I'm just not sure adding that semantics to null is the best idea, since
> null can be a variable value and having something like mb_substr($foo,
> 0, $this->length) suddenly behave differently when $this->length is null
> would be somewhat unexpected effect.

I don't deny that 'default' would be clearer than 'null' (and certainly  
clearer than 3 commas in a row), but I wouldn't call this strategy  
innovative. A lot of userland code out there uses NULL in this fashion.

I already had the opportunity to express my reservations about your  
proposal -- namely the effort required to purge ZEND_NUM_ARGS() usage vs  
the benefit, but since 1) you're apparently doing the work, 2) eases  
somewhat the way for named parameters, and 3) the default keyword was  
added, it doesn't seem so bad now.

And just to clear, I agree with Sara that ! (both for l/d/b and the  
pointer types) should not be redefined to "parameter was passed". But it's  
my understanding that that's not what you're planning.

-- 
Gustavo Lopes