PHP 7 Generator Return Type

generator_return_types.php

<?php
class Item {
    private $id;
    public function __construct(int $id)
    {
        $this->id = $id;
    }

    public function id() : int
    {
        return $this->id;
    }
}

class Collection {
    private $items = [];
    public function __construct(Item ...$items)
    {
        $this->items = $items;
    }

    public function item() : Generator
    {
        yield from $this->items;
    }
}

$items = [];
for ($i=0; $i<10; $i++) {
    $items[] = new Item($i);
}

$collection = new Collection(...$items);

$generator = $collection->item();
printf("\nThe Collection::item() method returns a type of %s, as expected\n", get_class($generator));
printf("However, it yields the following:\n\n");

foreach ($generator as $item) {
    printf("\tClass: %s. Calling id() method returns %d (%s)\n", get_class($item), $item->id(), gettype($item->id()));
}

printf("\n\nIt doesn't appear to be possible to hint the yielded type\n\n");

Probably. I do know that some people are pushing for generics. That should also bring the ability to create an "array of types" as well. Hopefully something like $foo = []bar; to create an array of bar objects

Here is working solution, where $items = []Item: https://3v4l.org/OH18b

Or better one: https://3v4l.org/YMQer

@gallna - It's not the prettiest or most obvious piece of code I've ever seen, but I like that last solution. It does what I need it to :) It's a shame that it's such a PITA to get it to do what we're trying to do, but it certainly does it here. Nice one!

hey @gallna - do you have another link for https://3v4l.org/YMQer by chance? That one produces a 500 and I am interested in your solution =) Thank you!

It works for me @rhift

<?php
class Item {
    private $id;
    public function __construct(int $id)
    {
        $this->id = $id;
    }
    public function id() : int
    {
        return $this->id;
    }
}
class Collection extends IteratorIterator
{
    public function __construct(Item ...$items)
    {
        parent::__construct(
            (function() use ($items) {
                yield from $items;
            })()
        );
    }
    public function current() : Item
    {
        return parent::current();
    }
}
$items = [];
for ($i=0; $i<10; $i++) {
    $items[] = new Item($i);
}
$collection = new Collection(...$items);

foreach ($collection as $item) {
    printf("\tClass: %s. Calling id() method returns %d (%s)\n", get_class($item), $item->id(), gettype($item->id()));
}

oh weird, thanks for pasting it @Antnee!