ZEND PHP 5 Certification STUDY GUIDE

Elements of Object-oriented Design ” 183
} else {
return ($this->current() % 2 == 1);
}
}
}
$numbers = new ArrayObject(range(0, 10));
$numbers_it = new ArrayIterator($numbers);
$it = new NumberFilter($numbers_it, NumberFilter::FILTER_ODD);
foreach ($it as $number) {
echo $number . PHP_EOL;
}
The accept() method simply determines whether any given element should be allowed
in the iteration; note that FilterIterator already implements all of the methods
of ArrayAccess, so that, effectively, from the outside our class can still be used as
an array.
This example outputs only the odd numbers stored in the array:
1
3
5
7
9
Summary
Object Oriented programming, coupled with Design Patterns—including those provided
by SPL—is the key to re-usable and highly modular code.
The more forethought you give your design, the more likely you are to be able to
re-use at least some of it, later, saving time and effort in the future—not to mention
that proper design techniques also make code easier to maintain and extend.
Bringing this experience to the table is what makes you truly versatile; as we mentioned,
design patterns are, after all, largely language- and problem-independent.
Licensed to 482634 - Amber Barrow (itsadmin@deakin.edu.au)