You can use not only an anonymous function but a closure, like e.g.
function ($a,$b) use ($sort) { ... }
and $sort will be available in the function body.
Self-contained example:
<?php
function getFn($sort) {
return function($a, $b) use($sort) {
if($a->$sort > $b->$sort) return 1;
if($a->$sort < $b->$sort) return -1;
return 0;
};
}
$abuseCases = array(
(object)array('ID'=>1, 'Sender'=>'Sender A'),
(object)array('ID'=>3, 'Sender'=>'Sender D'),
(object)array('ID'=>2, 'Sender'=>'Sender C'),
(object)array('ID'=>4, 'Sender'=>'Sender B')
);
echo "\n----- Sort By Sender ----\n";
usort($abuseCases, getFn('Sender'));
foo($abuseCases);
echo "\n----- Sort By ID ----\n";
usort($abuseCases, getFn('ID'));
foo($abuseCases);
function foo($a) {
foreach($a as $o) {
echo $o->ID, ' ', $o->Sender, "\n";
}
}
prints
----- Sort By Sender ----
1 Sender A
4 Sender B
2 Sender C
3 Sender D
----- Sort By ID ----
1 Sender A
2 Sender C
3 Sender D
4 Sender B
Update: With php<5.3 you can use an object instead of an anonymous function.
usort() expects the second parameter to be a callable
. That can be an anoymous function as of php 5.3, but it can also be the name of a function ....or an object and a method name passed as an array like array($obj, 'methodName')
.
$abuseCases = getData();
echo "\n----- Sort By Sender ----\n";
usort($abuseCases, array(new Foo('Sender'), 'compare'));
foo($abuseCases);
echo "\n----- Sort By ID ----\n";
usort($abuseCases, array(new Foo('ID'), 'compare'));
foo($abuseCases);
class Foo {
public $propName; // protected?
public function __construct($propertyName) {
$this->propName = $propertyName;
}
public function compare($a, $b) {
$prop = $this->propName;
if($a->$prop > $b->$prop) return 1;
if($a->$prop < $b->$prop) return -1;
return 0;
}
}
function foo($a) {
foreach($a as $o) {
echo $o->ID, ' ', $o->Sender, "\n";
}
}
function getData() {
return array(
(object)array('ID'=>1, 'Sender'=>'Sender A'),
(object)array('ID'=>3, 'Sender'=>'Sender D'),
(object)array('ID'=>2, 'Sender'=>'Sender C'),
(object)array('ID'=>4, 'Sender'=>'Sender B')
);
}
(If you make heavy use of this - or don't want to write excuses like this one -_- - you might want to define an interface like interface Comparator { ... }
, let Foo implement that interface and have some function/class that uses Comparator, i.e. a wrapper for objects around usort().)