1.2.368. Don’t Loop On Yield

Use yield from, instead of looping on a generator <https://www.php.net/`generator>`_ with yield.

yield from delegate the yielding to another generator <https://www.php.net/`generator>`_, and keep calling that generator <https://www.php.net/`generator>`_ until it is finished. It also works with implicit generator <https://www.php.net/`generator>`_ datastructure, like arrays. There is a performance gain when delegating, over looping manually on the generator <https://www.php.net/`generator>`_. You may even consider writing the loop to store all values in an array, then yield from the array.

<?php

function generator() {
    for($i = 0; $i < 10; ++$i) {
        yield $i;
    }
}

function delegatingGenerator() {
    yield from generator();
}

// Too much code here
function generator2() {
    foreach(generator() as $g) {
        yield $g;
    }
}

?>

See also Generator delegation via yield from.

1.2.368.1. Suggestions

• Use yield from instead of the whole foreach() loop

1.2.368.2. Specs

Short name	Structures/DontLoopOnYield
Rulesets	All, Suggestions
Exakat since	1.5.3
PHP Version	With PHP 7.0 and more recent
Severity	Minor
Time To Fix	Quick (30 mins)
Precision	High
Features	yield
Examples	Dolibarr, Tikiwiki
Available in	Entreprise Edition, Exakat Cloud