学习日记

Thinking in Patterns with Java V0.9: Chapter 13: Reducing interface complexity: TIPatterns.htm#_Toc41169743

1, Sections:

 Facade. 105

   Package as a variation of Facade  106

2, The main content and feeling:

  What is Facade? Bruce tell me:"If something is ugly, hide it inside an object.".

  After reading this chapter, I can got some below:

 

  1), Design pattern is really a pratical technique.

  Although I read this book, and know some of Facade, and know its example://:

facade:Facade.java, but, I feel I can't understand it without a real applying

of this pattern. Maybe, I will use it later.

  2), Just like Bruce's feeling:"To me, the Facade has a rather "procedural" (non-object-oriented) feel to it: you are just calling some functions to give you objects."

  3), Facade is most useful to C++ programmer, in java, "package" is a

build-in Facade.

 

3, Questions about programming:

  

  1), If it is that the function of Facade Pattern is only acting as a factory to create some objects? It can't call another object's method to process something in a static method just like below?

class A {   void f(){} } public class B {   static void doFinA() {     (new A()).f();   } }

  

Then, I can do something like this:

B.doFinA();

4, Questions about english language:

1), Strange words:

    cast about, mold, first-cut, tax adviser, tax code, mediator, as if, to be

fair, clash, majority

2), Difficult sentences:

 

                                     incomplete

Thinking in Patterns with Java V0.9: Chapter 12: System decoupling: TIPatterns.htm#_Toc41169737

1, Sections:

Observer. 95

Observing flowers. 97

A visual example of observers. 101

Mediator. 103

Exercises. 104

2, The main content and feeling:

This is a really difficult reading experience for me in this chapter's

learning. After three times' reading, at last, I can say, Observer Pattern, I

got it.

1), Observer Pattern

From my own understanding with a simplest instance, Observer Pattern can be used in the situation below:

I am prepairing for dinner, I am an Observable; My mother is reading a book in the book room and waiting for dinner, She is an Observer.

When the dinner is ready, I send her a signal: A dinner begin! From my

Observable role, I just:

 setChanged(){/*dinner has ready*/}

 super.notifyObservers(); //notify her the dinner has ready

And she just:

update(){/* put the book into desk, go the dinner room to eat */}

A key of this pattern must be aware:

The Observable object's class you used must inherit from the base class:

java.util.Observable !

Because, in the base Observable class, notifyObservers() don't call

setChanged() method, before you notify the Observer, you must call it in you

own derived-class which inherited from Observable base class; Otherwise,

although you have notified Observer, they notice that "changed" flag hasn't

changed, they don't update() anything. Just an Observer say: yes, I get you

notify, but, I see you don't change anything, so, I needn't do a useless

thing.

Note, in the book, Bruce say:

To get an effect, you must inherit from Observable and somewhere in your derived-class code call setChanged( ). This is the method that sets the ?changed? flag, which means that when you call notifyObservers() all of the observers will, in fact, get notified. In the example above setChanged( ) is simply called within notifyObservers( ), but you could use any criterion you want to decide when to call setChanged( ).

I understood his meaning is: You can put the setChanged() code in anywhere of

your code. But, I think if you want Observer update() himself, you must do a

setChanged() before you call notifyObservers() in the

Observable object. Is there any wrong with me?

 

Another point is important of my understanding is:

One Observable Object can be tied with many of different Observer Object

dynamically. Just like the book's example below:

...     f.opening().addObserver(ba.openObserver());     f.opening().addObserver(bb.openObserver());     f.closing().addObserver(ha.closeObserver());     f.closing().addObserver(hb.closeObserver());    ...

At last, the Observer Patterns descripted in this book is taken the use of standard java.util library. Of course, it must there are some other Observer Pattern implementions need me to learn.

2), Mediator

Sweep coupling under the rug, how is this different from MVC? MVC has distinct model and view; mediator could be anything. MVC a flavor of mediator

Why no more words in pattern of Mediator? So, I can't understand what is

Mediator. And, the sentence above I can't understand it yet. 

3, Questions about programming:

1), What is "callback"?

2), Notice, however, that the control of the flag?s state is protected, so that only an inheritor can decide what constitutes a change, and not the end user of the resulting derived Observer class.

   Who is "end user"?

3), Then it moves through the set and calls back to the update( ) member function of each Observer.

  Is there any "call back" action to the update() method of observer when observed object notify changes to observer?

4), What is Mediator Pattern?

5), Exercises.

4, Questions about english language:

1), Strange words:

Document-View Architecture, plot, textual, facilitate, potentially,

surrounding, observable, constitutes, in case, phenomena, have access to, come

in handy,

2), Difficult sentences:

Sweep coupling under the rug, how is this different from MVC?

MVC has distinct model and view; mediator could be anything. MVC a flavor of

mediator.

According to my learning, Sweep coupling under the rug, just like:(From

http://dict.cn)

sweep the dust under the carpet:

把不愉快的事情掩盖起来

 

                                     incomplete

一个令我感到有点骄傲的是：孩子的话我最懂!平时，她说的话，她的外婆和婆婆、甚至她的妈妈听几遍才能听得懂的话，基本上我一遍就能懂。也许，是我的耳朵比较灵敏吧：）

现在，自从上次孩子不在学校吃午餐后，每天早上送她去上幼儿园她都要问：今天哪个来接我？有时甚至中午送她去幼儿园都要问。可见，她是非常害怕在幼儿园里吃饭的，她怕一个人被留在幼儿园没人来接她。

孩子的记性也特别好，比如，我今天答应她，今天不买零食，明天给你买。于是，第二天，她就会问：爸爸，你昨天说的要给我买吃的。于是，我在惊叹于孩子的记忆力的同时，就不得不给她买了。

我们的孩子的所有情绪都会立即表现出来，所以，她说不喜欢我就是当时她的情绪对我不好。并不代表是一个她头脑里固定的概念，只是她当时心绪的反应。

我们孩子现在睡觉还可以了，原来睡觉不允许我们给她脱外衣，连身滚，而且睡得迟。现在一般9：00左右就睡了，睡之前也允许我们给她把外面的衣服脱了，只留内衣睡。早上也基本上能按时起来。只是有一点，她睡觉时爱把手伸出来，把手冻得冰冷。

这段时间，孩子在学写数字5了。在学校里，老师要求写一篇5。可能是她写的速度慢了，写不完，于是，在本子的后面全用叉填满。也算是写满一篇吧。

上次，连衣服称重有34斤了。是说，抱着去幼儿园挺累的。她不肯走路，如果不用自行车送她去幼儿园，就只有抱着或背着去了。送她去幼儿园是我的事，因为我上班就要经过她的幼儿园。

我们孩子的声音很大，说起话很响亮，有时争论起什么来，都怕她把嗓子震坏了。是否该教她说话、唱歌不要那么大声？又觉得好像不合适。

I can't remember that I have broken english learning how long time. But, this time, I have to restart english learning again. There is a good reason is: Next April, I will participate english test for 职称评定(professional rank and titles grading, I don't know if it is right).

Although, I have heard maybe the english test will cancel in a day, but, we can't know when this day come. So, a best way is to learn it, and prepair for english test.

Which way should I use to learn it?

1, write a sentence every day;

2, learning english program tutorial continuely, like Thinking in Patterns with Java;