流动性 用于创建流畅界面的工具。 方法链接 namespace DecodeLabs \ Fluidity ; interface Then { public function then ( callable $ callback ): Then ; public function thenEach ( iterable $ values , callable $ callback ): Then ; public function thenIf (? bool $ truth , callable $ yes , callable $ no = null ): Then ; public function thenUnless (? bool $ truth , callable $ no , callable $ yes = null ): Then ;