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Date: Sat, 16 Oct 2004 14:50:58 -0700
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Message-ID: <auto-000000463612@bobsilva.com>
Subject: RE: [PHP-DEV] Type hints with null default values
From: junkmail@bobsilva.com ("Robert Silva")
References: <20041016191353.85746.qmail@pb1.pair.com>

I think Marcus B's final comments in the original discussion are right on
track.

Stab: I voted for NULL type hinted arguments before I voted against them.

The main thing that changed my mind, is that in PHP there is no such thing
as a NULL object. I came to the conclusion that PHP wasn't broken, my
programming style/code was.

My opinion is that they should stay as they are now although personally.

Now with that said, I do think there needs to be a method to allow a type
hinted parameter to be optional (but not necessarily null).

class a {
	function b(Obj c=null) {};
}

$a->b(null) or $a->b($anything_not_an_Obj) would be an error.
$a->b() would be valid.

function Format(ZIFormatter $formatter=null)
{
	if (isset($formatter)) 
		return $formatter->Format($this);
	else return $this;
}

Now the argument can be made to not type hint $formatter to begin with, but
I don't want to have to check that it isnt null and instanceof ZIFormatter
interface. I just want to know if it was passed, that I can use it as a
ZIFormatter object.


Bob Silva


-----Original Message-----
From: Cristiano Duarte [mailto:cunha17@uol.com.br] 
Sent: Saturday, October 16, 2004 12:14 PM
To: internals@lists.php.net
Subject: [PHP-DEV] Type hints with null default values

Hi @ll,

Now that 5.0.3 is out, maybe it's time to bring back that
 old problem left in May: type hints and null default values.
This feature was dropped since no one could come with a
 reasonable solution.
So, for now, there is no (engine) way to have a parameter that
 can only be of some class or null. Am I right ?
The use of null (I know it's not a value it's a type...) is 
 justified because we don't have a "value" to represent 
 a NULL OBJECT(or NO OBJECT).
IMO, this is a necessary feature (maybe others thing this way
 too) and that's why I brought it back.

Cristiano Duarte

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