Stealth Generator

By Frederic Bouchery

<?php 

function foo(): iterable {
    return ['a'];
    yield 'b';
}

foreach(foo() as $v) {
    echo $v;
}

The code below has a useless loop. The presence of the yield keyword in the function body makes it a generator. As such, foreach() will react to yield calls, though the function returns immediately, without a yield. Hence, the empty loop, even though the function returns an array: indeed, to have the function behave as expected, it is necessary to remove the unreachable yield call, and then, the foreach() can use the return for the loop.

See Also

• Generator syntax
• stealth generator [Try me]

PHP Features

• generator
• yield

Last updated: 10 September 2026