[[RTS]BN+VS*]

Hey,

I have an abstract class with one final function, and 3 abstract ones. I'd like to call the abstract ones (so the code that will be put in the child classes) in the final function.

Is this possible? If yes: how?

Cheers
Jeroen De Dauw

[[RTS]BN+VS*]

This page demonstrates how to do this, but not for static functions (all my functions are static) : http://us2.php.net/m...p5.abstract.php

[Wimpy]

You can't have abstract static functions!

Quote

BN+VS*' date='23 Jul, 2009 - 03:22 AM' post='710586']
This page demonstrates how to do this, but not for static functions (all my functions are static) : http://us2.php.net/m...p5.abstract.php

[[RTS]BN+VS*]

Ok - they (the abstract ones) don't have to be static.

The problem I'm having is that the final function in my abstract class needs to be static (can't change that sadly). So apparently It's not possible to call abstract methods from there.

I suspect there are however some workarounds for this - for example the factory model? Any suggestions on which is best suited?

Cheers
Jeroen De Dauw

[Wimpy]

I think the final keyword would be useless for a static method since you can't override a static method/function. And no you can't call abstract methods from a static method since the static method does not belong to an instance which all implemented abstract methods would do. What you can do is to provide a class with a static method that require's an object instance that derives from a certain abstract class, and call that objects implemented version of the abstract method you need.

An example:

<?php
class MyClass
{
	public static function SayHello(MyOtherClass $obj)
	{
		$obj->TheFunction();
	}
}

abstract class MyOtherClass
{
	function TheFunction();
}


class MyDerivingClass extends MyOtherClass
{
	public function TheFunction()
	{
		echo "Hello World";
	}	
}

MyClass::SayHello(new MyDerivingClass());
?>

Hope it helps!


---- Edit

After thinking about it for 2 seconds you can actually do it like this as well:

<?php
abstract class MyClass
{
	public static function SayHello(MyClass $obj)
	{
		$obj->TheFunction();
	}
	function TheFunction();
}

class MyOtherClass extends MyClass
{
	public function TheFunction()
	{
		echo "Hello World";
	}	
}
MyClass::SayHello(new MyOtherClass());
?>

Quote

BN+VS*' date='23 Jul, 2009 - 03:06 PM' post='711085']
Ok - they (the abstract ones) don't have to be static.

The problem I'm having is that the final function in my abstract class needs to be static (can't change that sadly). So apparently It's not possible to call abstract methods from there.

I suspect there are however some workarounds for this - for example the factory model? Any suggestions on which is best suited?

Cheers
Jeroen De Dauw

This post has been edited by Wimpy: 23 July 2009 - 06:16 AM

[[RTS]BN+VS*]

Ok, thnx! This helped me out

Cheers
Jeroen De Dauw

[Wimpy]

Great!

Quote

BN+VS*' date='23 Jul, 2009 - 06:11 PM' post='711224']
Ok, thnx! This helped me out

Cheers
Jeroen De Dauw

[Wimpy]

It seems to be fine having abstract static functions in PHP! Sorry about that, I have been coding in C# for too long.

Wimpy, on 23 Jul, 2009 - 08:48 AM, said:

You can't have abstract static functions!

[AdaHacker]

Wimpy, on 25 Jul, 2009 - 07:08 AM, said:

It seems to be fine having abstract static functions in PHP! Sorry about that, I have been coding in C# for too long.

Actually, no, you were right the first time. I think. Sort of.

According to this page, as of PHP 5.2, abstract static methods are no longer allowed. However, this seems to be inconsistent between versions. On my Ubuntu box running PHP 5.2.6, trying to declare an abstract static method threw a fatal error. However, on my Windows box running PHP 5.2.9, it didn't show any error at all and, in fact, worked just fine. The main documentation on OOP doesn't really say anything one way or the other, so it seems like it's not really safe to dependon these working.

Either way, it might not help the OP anyway, because there's still the late static binding problem, which wasn't fixed until PHP 5.3. Since the static abstract functions would be resolved to the abstract parent class and not the child class, you couldn't call them from the final function in the abstract class anyway, because they'd have no implementation.

[Wimpy]

Thanks for sorting it out! I really thought I was correct the first time but when I was reading through some forums today I found someone actually using abstract static functions so I tried it on my Windows box (PHP 5.2.8, I think) and it was working just fine!

This post has been edited by Wimpy: 25 July 2009 - 11:31 AM

[[RTS]BN+VS*]

Thanks for the info guys