Preface

Let's start with a little story

Once upon a time , A consultant visited a client to investigate his development project . The core of the system is the inheritance system , The consultant looked at some of the code written by the developers . He found the whole system quite messy , The upper superclass makes some assumptions about the operation of the system , The next subclass implements these assumptions . But these assumptions don't apply to all subclasses , Lead to overwrite (override) Work It's very heavy . Just make a change in the superclass , You can reduce a lot of rewriting . In other places , Some of the intentions of the superclass are not well understood , So some of these behaviors are repeated within subclasses . There are other places , Several subclasses do the same thing , In fact, they can be moved to the top of the inheritance system .

The consultant then advised the project manager to look at the code , Put them in order , But managers are not keen on it , After all, the program seems to work , And the project faces a lot of schedule pressure . So the manager said , Take time to do this later .

The consultant also shared his ideas with the programmers working on the inheritance system , Tell them what might happen . Programmers are sharp , We can see the seriousness of the problem immediately . They know it's not all their fault , Sometimes it really takes an outside force to find problems . It took the programmer a day or two to sort out the inheritance system , And cut out half of the code , Function intact . They are very satisfied with this , and It's faster to add new classes to the inheritance system or use other classes in the system 、 It's easier .

The project manager is not happy . It's a tight schedule , There is a lot of work to do . The system has to be released in a few months , And these programmers spent two days in vain , The work done has nothing to do with most of the features to be delivered . The original code runs normally , Their new design seems a bit too much of a perfectionist . The project is to be delivered to the customer , Is code that can run efficiently , It's not the perfect thing to please the pedant . The consultant then suggested that this sort of arrangement should be carried out in other core parts of the system , This will put the whole project on hold for a week or two . All this work is just to make the code look more beautiful , It doesn't add any new features to the system .

How do you feel about the story ? You think the consultant's advice （ To further organize the program ） Is that right ? Will you follow that old engineering proverb :“ If it still works , Just don't touch it .”

So , The author created this book ---《 restructure 》, I'd like to share it with you

Adapt to people

The target audience of this book is Professional programmers , Those who write software for a living . Examples and discussions in the book , It involves a lot of code that needs to be read and understood in detail . These examples are all in the form of Java It's written in . The reason for choosing Java, Because it's a language that is more and more widely used , and Anything with C Language background People can easily understand it .Java Is an object-oriented language , The object-oriented mechanism is very helpful for refactoring .

Although the focus is on Code , but Refactoring for system design It also has a huge impact . It's also important for senior designers and architects to understand the principles of refactoring , And use refactoring technology in your own projects . It's better to have seniority 、 Experienced developers introduce refactoring techniques , Because such people are the best at understanding the principles behind refactoring , And adjust it according to the situation , Apply it to a specific area of work . If you don't use Java, This is especially important , Because you have to rewrite my example in other languages .

Now I want to tell you , How to make full use of it without reading the whole book .

If you want to know why you should refactor , Please read the first two chapters . They tell you what refactoring is and why it should be refactored .

The first 1 Chapter reconstruction , The first case

The first 2 Chapter reconstruction principle

 

If you want to know where to refactor , Please read before 5 Chapter . It will tell you some code features , These characteristics point to “ We need to refactor ”.

The first 3 Bad smell of chapter code

 

The first 4 Chapter 2 constructs the test system

The first 5 Chapter refactoring list

The first 6 Chapter reorganizing functions

The first 7 Chapter moves features between objects

The first 8 Chapter reorganizing the data

The first 9 In this chapter, we simplify the conditional expression

The first 10 Chapter simplifying function calls

The first 11 Chapter deals with general relations

The first 12 Chapter large reconstruction

You need this information ,

Official account ：Java Architects Alliance , Update the technology every day

 

If you want to start refactoring , From 5 The chapter extends to 12 Chapter . It can't be said to be a comprehensive list , It's just a start , It includes all the refactoring techniques I've sorted out in my work so far . I hope this is a part that you should review again and again in the future . Just skim the list at first , Look at some of them , You don't have to understand all the details . Once there is a real need to implement a code , Read it in more detail , Get help from . The list section is for reference , You don't have to read it all at once .

In addition, you should also read the list of other authors “ Guest section ”, Especially in the first 15 Chapter .

The first 13 Chapter reconstruction , Reuse and reality

The first 14 Chapter refactoring tool

The first 15 Chapter summary

So-called restructure （refactoring) It's a process like this : Without changing the external behavior of the code , Make changes to the code , To improve the internal structure of the program . Refactoring is a methodical method of program arrangement which has been formed through a lot of efforts , It can minimize the possibility of introducing errors in the finishing process . In essence , Refactoring is to improve the design of the code after it is written .

All right. , You need this information , Official account ：Java Architects Alliance , Update the technology every day