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Date: Tue, 07 Oct 2008 15:50:23 -0700
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Subject: RFC: SPL Comparator interface
From: jeremy@pinacol.com (Jeremy)

Something that would be extremely useful is a comparator interface in 
SPL, which could be used to easily implement sorting for objects.

Example:

class Foo implements Comparator
{
	// is numeric for this example
	public $bar;

	//implements compare method from Comparator interface
	public function compare($that)
	{
		//simple example; will return < 1 if this is less
		//than that; zero if they're equal; > 1 if this is
		//greater than that
		return $this->bar - $that->bar;
	}
}


Then, if I had an array of Foo objects, I could just call some kind of 
spl_sort function on the array which would use my comparator to sort them.

I realize this can be kludged with usort(), but I think there should be 
a better, OOP-ier way to do it.

I also realize that a similar effect could be achieved by defining an 
SPL PriorityQueue-ish collection rather than an array, but I think there 
ought to be a better way.  Java has a Comparator interface which works 
in much the same way, if that helps my case at all.

Jeremy