it-e-47 Object Orienta tion

OO can model a complex reality in a very natural way.
An example is "the cup of coffee". This shows interaction between customer, waiter and
Customer and kitchen don't know each other. The waiter is the intermediary. (Encapsulation).
Waiter and kitchen act differently to the request "a black coffee" (Polymorphism)
Both waiter and kitchen supply coffee (Inheritance).
The benefits of OO are higher for complex business processes. The more complex the better.
Different responsibilities, lots of exceptions, and processes that "look alike". Those are the ideal
ingredients for an OO approach.

Encapsulation means as much as shielding. Each
OO object has a shield around it. Objects can't "see" each
other. They can exchange things though, as if they are
interconnected through a hatch.
Customer, waiter and kitchen are three shielded objects
in the "cup of coffee" example. Customer and kitchen do not
know each other. The waiter is the intermediary between
those two. Objects can't see each other in an Object-oriented
world. The 'hatch' enables them to communicate and exchange coffee and money.
Encapsulation keeps computer systems flexible. The business process can change easily.
The customer does not care about the coffee brew process. Even the waiter does not care. This
allows the kitchen to be reconstructed, is only the "hatch" remains the same. It is even possible to
change the entire business process. Suppose the waiter will brew coffee himself. The customer
won't notice any difference.
Encapsulation enables OO experts to build flexible systems. Systems that can extend as your
business extends. Every module of the system can change independently, no impact to the other
Objects can respond differently to the same message. Both waiter as kitchen respond to"a
black coffee".
The actions are different though.
The waiter passes the message to the
kitchen, waits for response, delivers
coffee and settles the account.
The kitchen brews fresh coffee and
passes it to the waiter.
The same message with different
implementations, that is polymorphism.
Polymorphism makes Object-oriented systems extremely suitable for various exceptions and
exceptions to exceptions.
Similar, but just a little bit different. The world is full of exceptions and similarities. Object
Orientation places everything perfectly in a class tree.
Both waiter and cook are employees. So they both
have an employee number. This generic
employee number gets a generic place in
Both return a cup of coffee to the question "A
cup of coffee please". That similar behavior

also gets a generic place in Employee.
There are some exceptions. Waiter and
Cook have different methods to get a
cup of
coffee. Those specific methods get a
specific place, reusing the more generic
part in Employee.
No matter how complex your business
situation is, Object Orientation can cope with


1, intermediary  [,intə'mi:diəri]
adj. 中间的;媒介的;中途的
n. 中间人;仲裁者;调解者;媒介物

2, hatch  [hætʃ]
n. 孵化;舱口
vt. 孵;策划
vi. 孵化

3, cope  [kəup]
v. (with)竞争,对抗,对付,妥善处理
vi. 对付,妥善处理

Continue reading it-e-47 Object Orienta tion


setCapture一般用在drag move,resize的实现上。它只能在IE上使用,目的是为了捕获onclick, ondblclick, onmousedown, onmouseup, onmousemove, onmouseout, 和onmouseover这类鼠标事件,不让目标节点失去捕获。



Continue reading setCapture这个事,move,drag

it-e-46 Object-oriented programming

Object-oriented programming (OOP) refers to a special type of programming that combines
data structures with functions to create re-usable objects.
Otherwise, the term object-oriented is generally used to describe a system that deals primarily
with different types of objects, and where you can take the actions depends on what type of object
you are manipulating. For example, an object-oriented draw program might enable you to draw
many types of objects, such as circles, rectangles, triangles, etc. Applying the same action to each of
these objects, however, would produce different results. If the action is Make 3D, for instance, the
result would be a sphere, box, and pyramid, respectively.
Many languages support object oriented programming. In OOP data and functions are
grouped together in objects (encapsulation). An object is a particular instance of a class. [1] Each
object can contain different data, but all objects belonging to a class have the same functions
(called methods). So you could have a program with many e-mail objects, containing different
messages, but they would all have the same functionality, fixed by the email class. Objects often
restrict access to the data (data hiding).
Classes are a lot like types the exact relationship between types and classes can be complicated
and varies from language to language.
Via inheritance, hierarchies of objects can share and modify particular functions. You may
have code in one class that describes the features all e-mails have (a sender and a date, for
example) and then, in a sub-class for email containing pictures, add functions that display images.
[2]Often in the program you will refer to an e-mail object as if it was the parent (super-class)
because it will not matter whether the e-mail contains a picture, or sound, or just text. This code
will not need to be altered when you add another sub-class of e-mail objects, containing (say)
electronic cash.
Sometimes you may want an action on a super-class to produce a result that depends on
what sub-class it "really is". For example, you may want to display a list of email objects and
want each sub-class (text, image, etc) to display in a different colour. In many languages it is
possible for the super-class to have functions that sub-classes change to suit their own purposes
(polymorphism, implemented by the compiler using a technique called dynamic binding). So
each email sub-class may supply an alternative to the default, printing function, with its own
In many OO languages it is possible to find out what class an object is (run time type
information) and even what functions are connected with it (introspection / reflection). Others,
like C++ have little run time information available (at least in the standard language individual
libraries of objects can support RTTI with their own conventions).
[3]There are at least three approaches to OO languages: Methods in Classes, Multi-Methods
Separate from Classes, Prototypes.

Many languages follow Smalltalk in associating functions (methods) with classes. The
methods form part of a class definition and the language implementation will have (this is a
low-level detail hidden from the programmer) a vtable for each class which links methods to their
implementations. This indirection is necessary to allow polymorphism, but introduces a
performance penalty. In some languages (C++, at least), only some methods, marked as virtual
by the programmer, are treated in this way.

Some languages (e.g. common Lisp / CLOS) allow functions to specialise on the class of
any variable that they are passed (multi-methods). Functions cannot be associated with one class
because different versions of the function may exist for many different combinations of classes.

Other OO languages do away with classes completely (e.g. Self). Prototype-based languages
create new objects using an existing object as an example (prototype). Apart from solving some
problems with dynamic object creation, this approach also encourages delegation (function calls
are passed to other objects) rather than inheritance.


Continue reading it-e-46 Object-oriented programming


iOS平台目前主要泛指iPod Touch、iPhone以及iPad这三种主要的机型,近日开始研读起iOS Human Interface Guide(后简称HIG)的相关章节,发现其实有许多一般入门时常见的问题,其实都可以在这里获得解答。兹就经验上许多人可能会产生的疑问,并配合上述 HIG文件内容进行一份整理。 如同「平台特性(Platform Characteristics)」章节开头所明述的,成功的应用程序将会拥抱这些特性,并融合在让用户在操作装置之间,所以熟知iOS上的平台特性,合理的设计以及运用其在自己所开发的应用程序中,将会对于用户在操作应用程序时,有大大的帮助。
◆最舒适的点击区域大小是 44 x 44 点 (Points而非Pixels)

基本上,原则就是Home Screen如何,进入应用程序的默认显示方向就会是如何。
◆由于iPhone以及iPod Touch的主画面(Home Screen),只会有一种显示方向,所以默认进入到应用程序时,就应该会是直立向。



对,这听起来的确是很废话,在使用者的面前,只会有一个应用程序在前台与用户互动。在iOS 4之前,应用程序被关掉之后,就会被从内存中移除;但iOS 4之后,他可能会在背景继续执行,这个一般称之为多任务(Multitasking),应用程序通常会在背景执行直到他们下次被呼叫出来,或者直接被终止工作才会停止运作。
在主画面中,快速按Home Screen圆钮两次,就可以叫出位于画面最底端的多任务选单,使用者可以快速的找到最近用过的应用程序。当用户再一次使用这些应用程序的时候,这些程序就不用再重新被加载,而是会被从他们上次跳出的地方进入。
iOS应用程序是利用iOS SDK开发的应用程序,也可以称之为原生应用程序(Native App),由于这些iOS应用程序重组了内建应用程序的特色,所以依附在装置上之时,就可以在iOS环境下有特别的优势。人们会把这些应用程序当作像内建的相簿、行事历以及信箱。
◆网站应用程序(Web apps),行为近似于iOS应用程序,一般的网站应用程序通常会隐藏Safari浏览器的接口,让他看起来像是原生的应用程序。
◆优化网页(Optimized webpages),网页有针对iOS上的Safari浏览器进行优化,并移除一些不被支持的效果,像是Plug-In、Flash以及Java。更甚者,还会针对屏幕大小进行内容的排版调整等,以使得在装置上可以被最佳的阅读。
◆兼容网页(Compatible webpages),这是与上者相对的,网页可以在iOS上被浏览,但是通常会遇到一些无法支持的元素,排版之类的也不见得会适合在装置上阅读,但是通常都可以被显示出来。 在iOS用来浏览网页的Safari
在iOS上的Safari不支持 Flash、Java(含Java applets)或者第3方的网站内容插件。但支持HTML 5的以及 标签以提供影音串流,以及JavaScript、CSS 3以显示动画内容。

Continue reading 【转】苹果iOS平台成功的应用程序特性大整理

IPhone In Action 读书笔记

1章介绍,2-9章web,10-20章sdk(sdk tools)

mac os基于unix发展

480*320 像素输出屏幕。

wifi→EDGE(Enhanced Data Rate for GSM Evolution,增强型数据速率GSM演进技术,最大220kbps)→3G(384kbps--1000kbps)

web开发工具 iui库) ,dashcode(IDE)


1.4.1 web视图是980px缩放的效果?


            带url   不显示url

竖向 26%      13%

横向 35%     16%




第九章初步介绍了 objectC








不能包含ip voice功能





大部分将UI操作会和Cocoa Touch打交道,但是也有要使用ObjectC类的情况,这就在Core Foundation(类名以CF开头)之上了。

Cocoa Touch包含 UIKit(类名以UI开头)和Foundation(类名以NS开头)



第十九章讲图形 Quartz 2D,openGL等

Quartz 2D建立在老的Core foundation之上??


cocos2d是封装的openGL,也用到了quartz 2D

Quartz默认的坐标系是从右下到左上,与Cocoa Touch整好相反。如果你不是使用Cocoa Touch创建context,就要认为坐标原点是右下。



19.4.5 状态管理 save,restore.--和canvas2d像吧


19.7 动画介绍

19.8 OpenGL ES(Embded System)

EAGL is Embedded AGL(Apple's OpenGL extensions for OS X.)



详细见apple文档OpenGL ES Framework Reference,里面也有示例。

Continue reading IPhone In Action 读书笔记

iphone 那些事


主要的教程在 上找,

按照他的来,不懂得再google, 越的时候比较难操作的是进入DFU模式,那真叫技术活。


下一步开始更新cydia,但没wifi 怎么办,最后发现win7下Connectify可以直接做热点,哈哈,wifi是好了,但是cydia还是说什么网络错误。我找了新的源,任然如此。没办法,就按照里面提到的离线安装模式,使用iFunBox装了ipa补丁。



Continue reading iphone 那些事

it-e-45 How to Learn a New Language

How do you learn a new language? The fastest way is when you are forced to do so. But if
you're lucky enough to be learning by choice, you are probably doing it in your spare time and
you won't do that unless you are enjoying yourself  so choose an interesting project.
Choosing what you are going to write in your new language is more important than
choosing the language. Choose the language to suit the project or, better, choose both together.
For example, if you want to write something that will look good then don't choose a language
with no support for graphics.
Learn a little about the language before you start and try and find a solution that will play to
the language's new features. If you are using OOP for the first time, for example, try and think
how your project can be split into objects. If you are looking at functional programming, maybe a
numerical project would be a good start (I chose cryptography) (this suggestion does not imply
that functional languages are only useful for numerical code, just that most textbooks seem to
feature numerical examples in my limited experience making it easier to start in that
At the same time, be honest with yourself. Don't be too ambitious don't pick too difficult a
project and (maybe) don't pick too exotic a language. The second point is debatable. With any
language you will learn something new: it doesn't have to be a huge intellectual leap into the
unknown. You are going to be more productive in a language that has some familiar ideas, and
you can lean on that part of the language to get going. On the other hand, if you enjoy new ideas,
maybe you will be happier with something completely different.
Support is also important. If you intend to post questions to Usenet, is there an appropriate
newsgroup? Personally, I like booksÇthe best impetus for me is finding a good book on
computing that uses a particular language in the examples.
A note about asking for information on newsgroups: people seem to vary widely in how
precisely they talk about languages. At one end of the spectrum there are people who tend to rely
on a "subconscious" (or at least "sub-language") intuition and happily misuse terminology to "get
the idea across". At the other end are people who are very precise. Both, no doubt, will give
conflicting advice on how to learn and, sometimes, apparently conflicting answers to questions.
You have to learn to recognise different styles and read them in the context of the poster.
Finally, don't be afraid to change direction. I've stuck with a few languages much more than
with others. Sometimes I have given up in frustration. But even when you only play around a
little, you learn something. My argument is not that you must stay with a language a long time
to learn anything, but that the learning continues. Stay for a while and you'll learn something.
Stay longer and you'll learn more. there's no magic moment when you know everything (which
is what makes programming such a rewarding profession).

1, exotic  [,iɡ'zɔtik]
adj. 异国的;外来的;异国情调的

2, misuse  [,mis'ju:z, ,mis'ju:s]
vt. 滥用;误用;虐待
n. 滥用;误用;虐待
3, terminology  [,tə:mi'nɔlədʒi]
n. 术语,术语学;用辞
4, subconscious  [,sʌb'kɔnʃəs]
adj. 潜意识的;下意识的
n. 潜在意识;下意识心理活动
5, frustration  [frʌs'treiʃən]
n. 打破,挫折,顿挫
[计算机] 失败

Continue reading it-e-45 How to Learn a New Language

it-e-44 A Brief Word About Scripting

You've perhaps heard about something called scripting, or maybe you've heard of languages
like JavaScript, VBScript, Tcl and others (those languages are called scripting languages). You
may thus be wondering if scripting is the same as programming, and/or what the differences are,
and so on. People get quite passionate about this question, so I'm just going to cover it briefly and
technically. Here are some facts:
Scripting is essentially a type of programming.
Scripting languages have a few minor technical differences which aren't important to
discuss at this point.
Scripting languages tend to be interpreted rather than compiled, which means that you
don't need to compile them. they're compiled "on the fly" (i.e. when necessary, right
before they're run). This can make it faster to program in them (since you always have
the source code, and don't need to take the deliberate extra step of compiling).
The fact that scripting languages are interpreted generally makes them slower than.programming
languages for intensive operations (like complex calculations).
Scripting languages are often easier to learn than programming languages, but usually
aren't as powerful or flexible.
For programming things like applications for personal computers, you'll need to use a
programming language rather than a scripting language.
Scripting languages can be excellent for beginners: they tend to be easier to learn, and they
insulate you from some of the technical aspects of programming (compiling, for one). However,
if you're serious about programming, you won't be able to stay with a scripting language forever
you will move on to a programming language at some point. I'd say that it's good to know a
scripting language or two, and even to start with a scripting language rather than a programming
language. However, there's a point of view which says that, by protecting and "hand-holding" too
much, scripting languages don't properly prepare you for "serious" programming, and set you up
for a bit of a learning curve when you move on to a programming language.


1, deliberate  [di'libəreit]
a. 故意的,深思熟虑的
v. 仔细考虑
vt. 研讨

Continue reading it-e-44 A Brief Word About Scripting


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