既然是敏捷老师布置的，那当然得用些迭代渐进之类的方法吧
第一版就直接用story.tell()，这样直接可以满足五个要求里的四个了～

第二版加上单例模式啊，Story.getSingleton().tell()

第三版加上代理模式，StoryTeller.getSingleton().tell(Story.getSingleton())

第四版加上Adapter，我们没有StoryTeller只有Singer，怎么办呢
SingerStoryTellingAdapter<Singer>().tell(Story.getSingleton())

第五版，getter/setter貌似也是个设计模式是吧
SingerStoryTellingAdapter<Singer>()
.tell(Story.getSingleton().setText(story_text).getText())

第六版加上Factory模式啊
StoryTellerFactory<SingerStoryTellingAdapter<Singer>>()
.tell(Story.getSingleton().setText(story_text).getText())

第七版，一个Factory不够啊，怎么也得上Abstract Factory吧
abstract class TellerFactory {...}
abstract class StoryTellerFactory extends TellFactory {...}
class SimpleStoryTellerFactory extends StoryTellerFactory {...}

SimpleStoryTellerFactory<SingerStoryTellingAdapter<Singer>>()
.tell(Story.getSingleton().setText(story_text).getText())

第八版，来个Chain of Responsibility
abstract class TellerFactory {...}
abstract class StoryTellerFactory extends TellFactory {...}
class SimpleStoryTellerFactory extends StoryTellerFactory {...}

StoryTellingRequestHandler()
.setSuccessor(StoryTellingRequestConcreteHandler()
.setSuccessor(
SimpleStoryTellerFactory<SingerStoryTellingAdapter<Singer>()
)
)
.handleRequest(RequestType.TELL,
Story.getSingleton().setText(story_text).getText())

第九版，Builder和Prototype都用上了吧
story_text = StoryTextPrototypeBuilder().clone("Once upon a time...")

abstract class TellerFactory {...}
abstract class StoryTellerFactory extends TellFactory {...}
class SimpleStoryTellerFactory extends StoryTellerFactory {...}

StoryTellingRequestHandler()
.setSuccessor(StoryTellingRequestConcreteHandler()
.setSuccessor(
SimpleStoryTellerFactory<SingerStoryTellingAdapter<Singer>()
)
)
.handleRequest(RequestType.TELL,
Story.getSingleton().setText(story_text).getText())

第十版，Decorate一下，让字符串对象可以直接当作故事来讲
abstract class TellerFactory {...}
abstract class StoryTellerFactory extends TellFactory {...}
class SimpleStoryTellerFactory extends StoryTellerFactory {...}

void String::tellAsStory() {
story_text = StoryTextPrototypeBuilder().clone(this)
StoryTellingRequestHandler()
.setSuccessor(StoryTellingRequestConcreteHandler()
.setSuccessor(
SimpleStoryTellerFactory<SingerStoryTellingAdapter<Singer>()
)
)
.handleRequest(RequestType.TELL,
Story.getSingleton().setText(story_text).getText())
}

然后我们就可以这样用了：
"Once upon a time...".tellAsStory()

…………………………好吧叔叔不行了…………………………