Cannot Return Value from Generator

Why This Happens

PHP 5.x generators could only use return without a value. PHP 7.0 added support for return values in generators accessible via Generator::getReturn(). If you are on PHP 7+, you can return values but must call getReturn() on the generator to retrieve them.

The Problem

function fibonacci(): Generator {
    $a = 0;
    $b = 1;
    while (true) {
        yield $a;
        [$a, $b] = [$b, $a + $b];
    }
}
$gen = fibonacci();
$gen->next();
echo $gen->return; // Wrong way to get return value

The Fix

function fibonacci(int $limit): Generator {
    $a = 0;
    $b = 1;
    $count = 0;
    while ($count < $limit) {
        yield $a;
        [$a, $b] = [$b, $a + $b];
        $count++;
    }
    return $count; // PHP 7+ supports this
}
$gen = fibonacci(10);
foreach ($gen as $num) {
    echo $num . ' ';
}
echo 'Generated: ' . $gen->getReturn(); // Use getReturn()

Step-by-Step Fix

1. 1

   Check your PHP version

   Run php -v to see your version. Generator return values require PHP 7.0 or later.

2. 2

   Use getReturn correctly

   After the generator is fully consumed, call $generator->getReturn() to retrieve the return value.

3. 3

   Upgrade if needed

   If on PHP 5.x, either upgrade PHP or yield the final value and track it externally.