Simulating Python's With keyword with foreach and a trait in PHP

With.php

<?php // Pretty sure this doesn't clean up on exceptions, so keep that in mind

trait With
{
    abstract protected function enter(...$args);

    protected function exit($built, ...$initArgs)
    {
        // override this if needed
    }

    public function __invoke(...$args) : \Generator
    {
        $built = $this->enter(...$args);

        yield $built;

        $this->exit($built, ...$args);

        unset($built);
    }
}

class FilePointer
{
    use With;

    protected function enter($path, $mode)
    {
        return fopen($path, $mode);
    }

    protected function exit($fp, ...$args)
    {
        fclose($fp);
    }
}

foreach ((new FilePointer)('test.txt', 'w') as $fp) {
    fwrite($fp, "Hello World\n");
    var_dump($fp);
}

var_dump($fp);