Crisis Averted!: PHP 5, static and inheritance

Re: Parent

Brett (http://socket7.net) — Tue, 18 Aug 2009 20:19:12 -0700

Can you explain your solution a bit more? Swapping declarations as I assume you are suggesting is syntactically impossible. And even if it was possible it overwrites the parent's initial value, which is unacceptable.

class Cat extends Animal {
  parent::$color = 'Brown';
}

Parent

jagged software (http://facebook.com/jaggedsoft) — Tue, 18 Aug 2009 14:31:43 -0700

When using this example, your animals should say parent::$color = 'Brown';

More info on this issue

Robert — Tue, 11 Aug 2009 00:12:33 -0700

http://blog.felho.hu/what-is-new-in-php-53-part-2-late-static-binding.html

No title

Snap — Tue, 23 Jun 2009 00:18:03 -0700

Thank you all for you workarounds :)

Re: My Solution

bluedes (http://bluediamondsfx.181l.com) — Wed, 18 Mar 2009 07:11:30 -0700

That's nice, but when you have too many members, your array will get big. Accessing associative arrays is costly.

But still nice. ^_^

the singleton pattern

chris (http://www.ncoded.com) — Thu, 12 Feb 2009 09:45:14 -0800

ok "i think" that the way to do static members etc, is to use the singleton pattern; its definitly one of these patterns.

ok just to be clear, by static, i mean a data member that remembers its state across classes.

to be honest i cant remember if it holds up on inhertitance, i think you may have to use interfaces for that, not sure tho.

i am working tho a project at the momment which needs static members, so will update this post (if i remember) when i solve this.

No title

blaze — Fri, 26 Sep 2008 00:56:59 -0700

Ruby, in this aspect, is doing the right thing.

Catching Undefined Method errors

@KEM — Tue, 23 Sep 2008 08:49:54 -0700

Undefined methods will raise an E_FATAL_ERROR - the kind you can't catch.

However, as PHP is magical, there are various "Magic" function in PHP.

Check out the __callStatic magic function. This trick, in combination with class inheritance may provide you the functionality you are looking for.

Re: Web Developer

Brett (http://socket7.net) — Wed, 27 Aug 2008 14:10:24 -0700

Well, it's now August 2008, and PHP 5.3 is only in alpha. At least it's made the cut, along with a handful of other useful (and long-needed) features.

Web Developer

Matthew Grdinic (http://www.sledxchange.com) — Tue, 18 Dec 2007 16:55:12 -0800

PHP 5.3
Late Static Binding

Supposed to be out early 2008.

Re: No title

Brett (http://socket7.net) — Mon, 03 Dec 2007 13:12:18 -0800

Thanks for pointing this out Ben. There is hope!

No title

Ben (http://www.benlog.org) — Sat, 01 Dec 2007 19:43:59 -0800

PHP bug #42681 - status is 'assigned'.

If the class is instantiated

James — Wed, 28 Nov 2007 00:43:48 -0800

blah

propertyDefinitions = self::$propertyDefinitions;

// propertyDefinitions);

However I doubt this is the best solution. There should be the ability to do
$className::whatever without eval or something :/

Alternative to Tom's method

toby (http://bezoe.com) — Mon, 22 Oct 2007 01:03:37 -0700

I've used this method for getting a calling subclass's class constants. The problem is that the interpretor will not catch syntax errors in the eval until the statement is executed.



$className = get_class($this);

return eval("return $className::table;");

Possibility

KEM — Sat, 18 Aug 2007 20:34:31 -0700

this has been irking me for a while.

anybody know if you can catch "method undefined" errors with set_error_handler? no luck yet... i'm not exactly sure what kind of error that is. it may not be "catchable".

dirty, but (hypothetically):

<?php
	function myErrorHandler($errno, $errstr){
		$info = debug_backtrace();
		// if called on a subclass of Record, divert to a call to 
		// Table::find with the correct $table argument
	}
	set_error_handler('myErrorHandler');

	class Table {
		public static function find($table){
			// ...
		}
	}
	
	// dummy
	abstract class Record {}
	
	class Person extends Record {
		public static $table = 'People';
	}
	
	Person::find();

?>

that would keep the classes nice and clean…

Re: My solution

Brett (http://socket7.net) — Sun, 15 Jul 2007 19:41:08 -0700

I like your solution for its brevity. I also like that for each new class it's only a small method to implement; it's very well contained. I've never liked my solution of passing variables around like a fool; that's incredibly messy.

Thanks for sharing.

My Solution

Tom Lancaster (http://www.newhanoian.com) — Wed, 11 Jul 2007 22:25:42 -0700

static $table;

 protected function table() {
	$vars = get_class_vars(get_class($this));
	return $vars['table'];
}

Exactly the same problem

Jonovic — Mon, 09 Jul 2007 11:43:02 -0700

This is realy pain in the a.. My solution for this time is to turn to dynamic objects and forget the static classes for a while. I have been working around the database access objects with the help of design patterns.

Re: Workaround?

Brett (http://socket7.net) — Sat, 05 May 2007 14:54:34 -0700

I worked around it in two ways, neither of which are great. One of the ways is to set a member variable in the constructor. This makes the value available within the object as well as from the outside, though it is not static. Obviously not a great solution.

The second way I've worked around this is to pass an extra class name parameter into the static method calls telling the method which class it should 'act as.' Again, not a great solution.

If you're willing to put up with the lack of purity, these two options work well enough. Hopefully some future version of PHP will address this.

Workaround?

Tom Lancaster (http://www.newhanoian.com) — Wed, 02 May 2007 22:20:27 -0700

I'm having this exact same problem. In my case I'm subclassing an abstract actsastree for different db tables. Of course I have the table name as a static member, and of course it doesn't work.

I'm interested to know how you work around this.