PHP Generators

1. PHP GENERATors

2. SPOILER
Almost everything you can do with generators can be done with an Iterator
- Generators are just a handy way to create an iterator
- YIELD has the power
- Some magic

3. me!Simone Di Maulo
You can find me at @toretto460
Software Engineer
[“AdEspresso” | [“Kataskopeo” | [“Terravision” | [“Freelance”]]]]

4. ITERAtors

5. interface Iterator extends Traversable
{
abstract public mixed current ( void )
abstract public scalar key ( void )
abstract public void next ( void )
abstract public void rewind ( void )
abstract public boolean valid ( void )
}

6. let’s

7. We need to maintain internal index to track the current and next
pointer
rewind() just resets the index so that current() and next() will work
as expected.
Keys don’t have to be numeric!
Iterator implementation

8. “Generators provide an
easy way to implement
simple iterators without
the overhead or complexity
of implementing a class
that implements the
Iterator interface.”
generators

9. YIELD

10. function lines($file) {
$handle = fopen($file, "r");
while (!feof($handle)) {
yield trim(fgets($handle));
}
fclose($handle);
}
$lineReader = lines(__DIR__ . '/test.php');
var_dump($lineReader);
// object(Generator)#1 (0) {
// }

11. let’s

12. COROUTINES

13. Coroutines are computer program components that
generalize subroutines for non preemptive multitasking,
by allowing multiple entry points for suspending and
resuming execution at certain locations.
COROUTINES

14. $gen = call_user_func(function (array $data) {
foreach ($data as $item) {
// do something before
yield $item;
// do something after
}
});
foreach ($gen as $item) {
doSomethingWith($item);
}
before $item0
doSomething($item0)
after $item0
before $item1
doSomething($item1)
after $item1

15. let’s

16. Easy to create
Can be delegatedyield from <expr>
The engine creates
an iterator for
you!
Just yield the values

17. THANKS!Any questions?