Type hints with null default values

Am Sa, den 16.10.2004 schrieb Cristiano Duarte um 21:13:

Hi @ll,

Now that 5.0.3 is out

Doohh 5.0.3? I didn't see any announcement and I planned to commit
several stuff before :(

/Georg

Georg Richter, Senior Software Developer
MySQL AB, www.mysql.com

See you at MySQL ComCon Europe November 8-10!
www.mysqlcomconeurope.com

Cristiano Duarte wrote:

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.

I'm also realing waiting for this implemented. Since I've started to use the new features of v5, I've had to deal with parameter checks in exactly this way. If it's not class/interface instanceof type x, throw an exception. I just hope, if it gets implemented, it's done via exceptions too.

• Markus

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