Do not call generator functions directly, that won't work.
<?php
function my_transform($value) {
var_dump($value);
return $value * 2;
}
function my_function(array $values) {
foreach ($values as $value) {
yield my_transform($value);
}
}
$data = [1, 5, 10];
// my_transform() won't be called inside my_function()
my_function($data);
# my_transform() will be called.
foreach (my_function($data) as $val) {
// ...
}
?>