Flow\Template::setAttr PHP Method

    public function setAttr(&$obj, $attrs, $value)
    {
        if (empty($attrs)) {
            $obj = $value;
            return;
        }
        $attr = array_shift($attrs);
        if (is_object($obj)) {
            $class = get_class($obj);
            $members = array_keys(get_object_vars($obj));
            if (!in_array($attr, $members)) {
                if (empty($attrs) && method_exists($obj, '__set')) {
                    $obj->__set($attr, $value);
                    return;
                } elseif (property_exists($class, $attr)) {
                    throw new \RuntimeException("inaccessible '{$attr}' object attribute");
                } else {
                    if ($attr === null || $attr === false || $attr === '') {
                        if ($attr === null) {
                            $token = 'null';
                        }
                        if ($attr === false) {
                            $token = 'false';
                        }
                        if ($attr === '') {
                            $token = 'empty string';
                        }
                        throw new \RuntimeException(sprintf('invalid object attribute (%s) in %s line %d', $token, static::NAME, $this->getLineTrace()));
                    }
                    $obj->{$attr} = null;
                }
            }
            if (!isset($obj->{$attr})) {
                $obj->{$attr} = null;
            }
            $this->setAttr($obj->{$attr}, $attrs, $value);
        } else {
            if (!is_array($obj)) {
                $obj = array();
            }
            $this->setAttr($obj[$attr], $attrs, $value);
        }
    }