Generator with reference not working

Question

Given the following code

public static function &generate($arr)
{
    foreach ($arr as $key => $value) {
        yield $key => $value;
    }
}

This static method should yield $key => $value by ref on each array iteration

Then I use the static method in another class:

$questions = $request->questions;

foreach (self::generate($questions) as &$question) {
    $question['label'] = json_encode($question['label']);

    ... other code
}

unset($question);

die(var_dump($questions[0]['label']));

I should have a json encoded string but I always have an array, I don't understand why.

• The questions attribute in the $request var doesn't exist, it is returned by the magic method __get (questions is inside of an array so the value is returned by __get)
• If I remove the generate method and give $questions to my foreach, it works and I have my json encoded string

Answer 1

You need to ensure pass-by-reference "all the way through"

public static function &generate(&$arr)
{
    foreach ($arr as $key => &$value) {
        yield $key => $value;
    }
}

for both $arr and $value