Handy "chain()" helper method for making non-fluent classes/objects fluent.

chain_helper.php

<?php

function chain($object)
{
    return new class ($object) {
        protected $lastReturn = null;

        public function __construct($object)
        {
            $this->wrapped = $object;
        }

        public function __toString()
        {
            return (string) $this->lastReturn;
        }

        public function __call($method, $params)
        {
            if (($index = array_search('{carry}', $params)) !== false) {
                $params[$index] = $this->lastReturn;
            }

            $this->lastReturn = $this->wrapped->{$method}(...$params);

            return $this;
        }
    };
}

It will always throw a BadMethodCallException, won't it?

Probably a guard with method_exists() would be sufficient.