Iterable in PHP | vadnica.org

OOP Basics: Iterable

The iterable data type (introduced in PHP 7.1) combines arrays and objects that implement the Traversable interface. This allows us to write a function that accepts anything that can be looped through using a foreach loop.

iterable allows functions to accept both arrays and objects simultaneously.

By implementing the IteratorAggregate or Iterator interfaces, we can transform our own objects into data collections.

EXAMPLE

[file:1. Basic Iterable (Array and Object)]
<?php
// The function accepts any iterable type
function printIterable(iterable $data) {
    foreach ($data as $item) {
        echo $item . " ";
    }
}

// 1. Usage with an array
printIterable([1, 2, 3]);

echo " | ";

// 2. Usage with an object (updated for PHP 8.1+)
class MyCollection implements IteratorAggregate {
    private $data = [4, 5, 6];

public function getIterator(): Traversable {
        return new ArrayIterator($this->data);
    }
}

$collection = new MyCollection();
printIterable($collection);
?>

[file:2. IteratorAggregate (Collection)]
<?php
class Collection implements IteratorAggregate {
    private array $items = ["First", "Second", "Third"];

public function getIterator(): Traversable {
        return new ArrayIterator($this->items);
    }
}

$myCollection = new Collection();
foreach ($myCollection as $thing) {
    echo $thing . "<br>";
}
?>

[file:3. Advanced Iterator Implementation]
<?php
class MyIteration implements Iterator {
    private int $position = 0;
    private array $items = ["Apple", "Banana", "Cherry"];

public function current(): mixed { return $this->items[$this->position]; }
    public function key(): mixed { return $this->position; }
    public function next(): void { ++$this->position; }
    public function rewind(): void { $this->position = 0; }
    public function valid(): bool { return isset($this->items[$this->position]); }
}

$fruit = new MyIteration();
foreach ($fruit as $name) {
    echo $name . " ";
}
?>

RESULT

The result will be displayed here...