public function addInterface($interface) {
		if ($interface instanceof PhpInterface) {
			$name = $interface->getName();
			$qname = $interface->getQualifiedName();
			$namespace = $interface->getNamespace();

			if ($namespace != $this->getNamespace()) {
				$this->addUseStatement($qname);
			}
		} else {
			$name = $interface;
		}

		$this->interfaces->add($name);

		return $this;
	}