Code reading methods and best practices

introduction

Reading code is a basic skill of programmers , It is also software development 、 maintain 、 evolution 、 An integral part of the review and reuse process . This paper takes reading code as an independent topic for the first time , Systematically discuss . Open source projects — It is a treasure house that all programmers should cherish .

This article focuses on code , Related knowledge and skills are discussed in detail .“ His shan zhishi 、 Can offend jade ”, Read and learn this article carefully , It can quickly improve readers' code reading skills and skills , Then from the existing excellent code 、 Algorithm 、 The architecture 、 Draw nutrition from design , Improve their own development and design ability .

Code reading has its own set of skills , It is important to be able to determine when to use which technology . This article uses several practical examples , Show readers how to distinguish good （ And bad ） Code , How to read , What should be paid attention to , And how to use this knowledge to improve your code .

Get into the habit of reading high-quality code , It can improve the ability of writing code .

There is a window , Never opened , But it should be closed forever ;
There are some people , Do exist , But we have no chance to meet ;
There is a life , Not yet , But we have left forever .

Good code ： Beautiful as music

Good programs are like good music , They are done so skillfully , So perfect , Reflect the beauty without words . Just as good music can change your view of life , Let you re-examine your life , It's the same as people who communicated across time and space many years ago .

As a software developer , Good procedure , What it can bring , Not inferior to the impact of music .

Even harder to come by , These valuable procedures are often not made by " Authority figures "、" Renowned experts at home and abroad " Written by , They are written by ordinary programmers . These programmers are no different from readers . Although these programmers are not all powerful figures , But majors make experts , Focus on a certain field for a long time , We can create a wealth that all programmers should cherish .

Just like the ancient Michelangelo , Compared with those famous bishops at that time 、 For the nobility , How insignificant he is , But to this day , Those people and their names are gone with the wind , The glory of the past faded with time , Michelangelo's name is engraved in the hearts of most even ordinary people , Many people can think of those perfect sculptures ---" David "、" Genesis ". This honor may be unparalleled in the history of literature and Art .

Everything changes from quantity to quality

We are programmers .
Our work （ In many cases , And our passion ） Is to create new things by writing code .PRD、UED draft 、 Lots of illustrations 、 Detailed project schedule 、 Piles of thick design documents cannot meet the needs of users . These are wishes , Design , Express what we want to achieve . Only by writing code can we deliver something that really meets the needs of users ： Code is real 、 Really 、 Down to earth .

I'm afraid , No great novelist , Never read anyone else's work , No great painter , Never studied other people's paintings , There is no skilled surgeon , I have never seen how to operate on the same thing , No captain is not the first to watch how to actually operate from the co pilot's position .

Analogy from here to there , We can easily understand ： The way to write great code is to read it , Read a lot of code ： High quality code 、 Low quality code ; Assembly language code 、C Code 、C++ Code 、Java Code 、PHP Code 、Go Code 、Kotlin Code 、TypeScript Code 、Haskell Code 、Lisp Code , Code written by strangers thousands of miles away , And the code we just wrote last week . because , If not , We will constantly redo what others have already done , Repeating the past has
The successes and mistakes that have happened .

Reading the code

What we observe is not nature itself , It's nature's characteristics under the observation methods we use .
—Werner Heisenberg

Pass the correct code review , You can find 90% Software error .

The time programmers spend on software , More than half are reading 、 Maintain others' code .

Code reading has become a basic skill of software engineers nowadays . Besides , Read the actual 、 Write good code , You can have a deeper understanding of how to construct and write important systems , You can't learn this ability just by writing small programs .

In the work of programmers , A large part of the content is reading 、 understand 、 And modify the original （ Write it yourself and others ） Code . Legacy code continues 、 Inevitable accumulation , Emphasis on software reuse , The high mobility of personnel in the software industry and other factors , Have caused the work to be extremely complex 、 The challenge is great .

Get into the good habit of spending time reading high-quality code written by others .

Just like reading high-quality prose can enrich vocabulary 、 Stimulate imagination 、 Expand your mind , Analyzing the internal structure of a well-designed software system can learn new architectural patterns 、 data structure 、 coding method 、 Algorithm 、 Style and document specifications 、 Application programming interface (API), Even new computer languages .

Read high quality code , It can also improve your coding level .

Code readability

I regret to tell you that , Just recently , I checked my program again （ Quality factor and tic tac toe game ), They didn't
There are comments or documents in any form .
I regret to report that I've just recently looked again at my programs for prime factors and tic-tac-toe, and they are entirely free of any sort of comments or documentation.
—Donald E. Knuth

When writing a program, you should consider making it easy to read , also , Whether the program is easy to read , People need to read them .

Write readable code , To be human and to be self , It is all due to the contemporary , A great good thing that will benefit the future .

reusing

Reading code may also be to find reusable components . But don't expect too much .
The reusability of code is very attractive , But it's hard to master . Lower your expectations and you won't feel disappointed .

Writing reusable code is difficult .

these years , Only a few software can stand the test of time , It is reused in many different solutions . Software components generally need to be expanded gradually , And repeated rewriting to apply to two or three different systems , Will become reusable components .

Software developed for special purposes rarely meets these conditions . actually , According to the software cost model (software cost model), Writing reusable software may increase 50% Development workload of .

Read the code motto

1. When analyzing a program for the first time ,main Is a good starting point .

2. To develop , It's a good habit to spend time reading high-quality code written by others .

3. Pay attention to and pay attention to the special non functional requirements in the code , These requirements may lead to specific implementation styles .

4. In the search for bug when , Please analyze the code from the manifestation of the problem to the root of the problem . Don't follow irrelevant paths （ Go astray ).

5. Make full use of the debugger 、 Compiler gives warnings or outputs symbolic code horse 、 System call tracker 、 Logging mechanism 、 Package dump tool and message detection program , location bug The location of .

6. From feature function description to code implementation , You can use keywords to search for relevant codes .

7. Refactoring , Start with a working system , And make sure that at the end , The system works properly . A proper set of automated test cases (test case) highly necessary .

8. When starting a new software system , it is to be noted that , The system is made up of many parts , Not just executing statements . also
   Pay attention to the following contents ： File and directory structure 、 Generation and configuration process 、 User interface and system documentation .

9. There are many alternative strategies for code reading ： Bottom up and top down analysis 、 Apply heuristics and check comments and external documents , It should be based on the needs of the problem , Try all these methods .

10. Creative code layout can be used to improve the readability of code . You can use spaces 、 Temporary variables and parentheses improve the readability of expressions . You can use good indentation and wise choice of variable names , Improve the readability of poorly written programs .

11. To write 、 When reading the code , Get into the habit of adding comments .

12. World affairs , It must be done in detail ; It's difficult in the world , Make it easy . To solve the difficult code, start with the easy part .

Conclusion

The sunset , Make a cup of tea , Close your notebook , Knead the old waist that has been sitting for a long time , Stretch your arms , Look out the window at the distant mountains . Is there some " Picking chrysanthemums under the east hedge , Leisurely see the south mountain " Artistic conception ? It's just that TaoYuanming grows chrysanthemums , What we sow and harvest is code .