http://3v4l.org/tTreF -- PHP 5.6 example of "Functional Options" as presented by Rob Pike in his article "Self-referential functions and the design of options" http://commandcenter.blogspot.com.au/2014/01/self-referential-functions-and-design.html

mailer.php

<?php

/**
 * PHP 5.6 example of "Functional Options" as presented by Rob Pike
 * in his article "Self-referential functions and the design of options"
 * http://commandcenter.blogspot.com.au/2014/01/self-referential-functions-and-design.html
 */

namespace Mailer {
    class Mailer {
        private $host;
        private $lazy = false;

        // ... is variadic function syntax. See: http://php.net/manual/en/functions.arguments.php#functions.variable-arg-list
        public function __construct($host, ...$options) {
            $this->host = $host;

            foreach ($options as $option) {
                $option($this);
            }
        }

        // Wish this could be a private function and still be
        // invoked by an options function so it's not mutable from the outside
        public function setLazy($lazy) {
            $this->lazy = $lazy;
        }

        public function isLazy() {
            return $this->lazy;
        }
    }
}
namespace Mailer\Options {
    class Lazy {
        public function __invoke(\Mailer\Mailer $mailer) {
            $mailer->setLazy(true);
        }
    }

    function SuperLazy() {
        return function(\Mailer\Mailer $mailer) {
            $mailer->setLazy(true);
        };
    }
}

namespace {
    use function \Mailer\Options\SuperLazy;

    // Anonymous functions configure Mailer
    // Wire up as many as needed for optional settings and pass as constructor arguments
    $tls = function (\Mailer\Mailer $mailer) {
        echo 'LOL Lets do some TLS --';
    };


    // Any one of these $lazy vars can be passed as options arguments
    // 1. Anonymous function
    $lazy1 = function (\Mailer\Mailer $mailer) {
        $mailer->setLazy(true);
    };
    // 2. Object that responds to being used like a function via __invoke()
    $lazy2 = new \Mailer\Options\Lazy;
    // 3. Namespaced function (must return an anonymous function)
    $lazy3 = SuperLazy();

    $mailer = new \Mailer\Mailer('www.gmail.com', $tls, $lazy3); // Add any function options to your liking

    echo $mailer->isLazy() ? 'Yes lazy' : 'No lazy';
}