PHP iterable to array or Traversable

Question

I'm quite happy that PHP 7.1 introduced the iterable pseudo-type.

Now while this is great when just looping over a parameter of this type, it is unclear to me what to do when you need to pass it to PHP functions that accept just an array or just a Traversable. For instance, if you want to do an array_diff, and your iterable is a Traversable, you will get an array. Conversely, if you call a function that takes an Iterator, you will get an error if the iterable is an array.

Is there something like iterable_to_array (NOT: iterator_to_array) and iterable_to_traversable?

I'm looking for a solution that avoids conditionals in my functions just to take care of this difference, and that does not depend on me defining my own global functions.

Using PHP 7.1

Answer 1

Not sure this is what are you searching for but this is the shortest way to do it.

$array = [];
array_push ($array, ...$iterable);

I'm not very sure why it works. Just I found your question interesting and I start fiddling with PHP

Full example:

<?php

function some_array(): iterable {
    return [1, 2, 3];
}

function some_generator(): iterable {
    yield 1;
    yield 2;
    yield 3;
}

function foo(iterable $iterable) {
    $array = [];
    array_push ($array, ...$iterable);
    var_dump($array);

}

foo(some_array());
foo(some_generator());

It would be nice if works with function array(), but because it is a language construct is a bit special. It also doesn't preserve keys in assoc arrays.