Code quality

Июль 31, 2022

Содержание

2. Tell me, what is a clean code for you?
3. for (i = 0;i 0 && char_code
4. void CEquation::trio(double array[][rt+1],double alfa[][rt+1]) { for (int L = 0; L
5. Good vs Bad
6. How to write beautiful code There are two parts to learning craftsmanship: knowledge and work. You
7. 80% of the lifetime cost of a piece of software goes to maintenance. Hardly any software
8. Why do we see a bad code? Time: I don't have a time We never seem
10. Naming is important
11. The name should represent the developer’s idea int d; // time from beginning int elapsedTimeInDays; int
12. The name should represent the developer’s idea public List getThem() { List list1 = new ArrayList
13. The name should represent the developer’s idea public List getFlaggedCells() { List flaggedCells = new ArrayList
14. Use meaningful difference public static void copyChars(char a1[], char a2[]) { for (int i = 0;
15. Use meaningful names private Date genymdhms; private Date modymdhms; private final String pszqint = "102"; VS
16. Use searchable names #define CFT_CNT 13 #define SSIM_CLS_CNT 4096 #define PX_BUFF_CNT 10000
17. Class names Classes and objects should have noun or noun phrase names like Customer, WikiPage, Account,
18. Method names Methods should have verb or verb phrase names like postPayment deletePage, or save. Accessors,
19. Method Names Should Say What They Do Date newDate = date.add(5); Would you expect this to
20. One function – one operation Functions (aka methods)
21. Functions (aka methods)
22. F1:Too Many Arguments Functions should have a small number of arguments. No argument is best, followed
23. F3: Flag Arguments Boolean arguments loudly declare that the function does more than one thing. They
24. I’ll leave the project when complete all my technical debt
25. Code review Each team member review the code and writing comments/recomendations It’s a primary responsibility of
26. Comments C1: Inappropriate Information Change histories(?) Authors(?) Date of last update(?) C2: Obsolete Comment It is
27. Comments C3. Redundant Comment Don’t comment what a code does – I can read the code
28. Comments C4: Poorly Written Comment Comments should say Why or purpose, not how C5: Commented-Out Code
29. General G1: Multiple Languages in One Source File a Java source file might contain snippets of
30. General G5: Duplication Every time you see duplication in the code, it represents a missed opportunity
31. General G5: Duplication (cont) modules that have similar algorithms, but that don’t share similar lines of
32. General G6: Code at Wrong Level of Abstraction Good software design requires that we separate concepts
33. General G7: Base Classes Depending on Their Derivatives The most common reason for partitioning concepts into
34. General G9: Dead Code You find it in the body of an if statement that checks
35. General G11: Inconsistency If you do something a certain way, do all similar things in the
36. General G23: Prefer Polymorphism to If/Else or Switch/Case “ONE SWITCH” rule: There may be no more
37. General G28: Encapsulate Conditionals if (shouldBeDeleted(timer)) is preferable to if (timer.hasExpired() && !timer.isRecurrent())
38. General G29: Avoid Negative Conditionals if (buffer.shouldCompact()) is preferable to if (!buffer.shouldNotCompact())
39. General G35: Keep Configurable Data at High Levels
40. One more Clear, not Clever Don’t be clever, instead be clear “I never make stupid mistakes.
41. What is “code smell”? Wiki say: In computer programming, code smell is any symptom in the
42. The most “popular” code smells
43. Bad vs. Clean code What is the clean code? What is the bad code? Characteristics of
44. What do you know now? What is Code Smell It’s a feeling or sense that something
45. How to improve code quality?
47. Скачать презентацию

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Tell me, what is a clean code for you?

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for (i = 0;i < strlen(line);i++) { short char_code = isupper(line[i])

? line[i] - 64 : line[i] - 96; if (char_code > 0 && char_code < 27) { printf("%c", isupper(line[i]) ? ((char_code + step) % 26 + 64) : ((char_code + step) % 26 + 96)); } else { printf("%c", line[i]); } }

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void CEquation::trio(double array[][rt+1],double alfa[][rt+1]) { for (int L = 0; L

1+L; k

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Good vs Bad

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How to write beautiful code
There are two parts to learning craftsmanship:

knowledge and work. You must gain the knowledge of principles, patterns, practices, and heuristics that a craftsman knows, and you must also grind that knowledge into your fingers, eyes, and gut by working hard and practicing.
(Robert C. Martin, Clean code)

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80% of the lifetime cost of a piece of software goes

to maintenance.
Hardly any software is maintained for its whole life by the original author.
Code quality improve the readability of the software, allowing engineers to understand new code more quickly and thoroughly.

Why its important?

Слайд 8

Why do we see a bad code?
Time: I don't have a

time
We never seem to have time to do it, but always seem find time to redo it?!
Knowledge: what is a good code?
Tools: I don’t know about it
Skills: I can’t do it

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Слайд 10

Naming is important

Слайд 11

The name should represent the developer’s idea
int d; // time from

beginning
int elapsedTimeInDays;
int daysSinceCreation;
int daysSinceModification;

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The name should represent the developer’s idea
public List getThem() {
List list1

= new ArrayList();
for (int[] x : theList)
if (x[0] == 4)
list1.add(x);
return list1;
}
What kinds of things are in theList?
What is the significance of the zeroth subscript of an item in theList?
What is the significance of the value?
How would I use the list being returned?

Слайд 13

The name should represent the developer’s idea
public List getFlaggedCells() {
List flaggedCells

= new ArrayList();
for (int[] cell : gameBoard)
if (cell[STATUS_VALUE] == FLAGGED)
flaggedCells.add(cell);
return flaggedCells;
}

Слайд 14

Use meaningful difference
public static void copyChars(char a1[], char a2[]) {
for (int

i = 0; i < a1.length; i++) {
a2[i] = a1[i];
}
} VS
source and destination are used for the argument
names

Слайд 15

Use meaningful names
private Date genymdhms;
private Date modymdhms;
private final String pszqint

= "102";
VS
private Date generationTimestamp;
private Date modificationTimestamp;;
private final String recordId = "102";

Слайд 16

Use searchable names
#define CFT_CNT 13
#define SSIM_CLS_CNT 4096
#define PX_BUFF_CNT 10000

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Class names
Classes and objects should have noun or noun phrase names

like Customer, WikiPage, Account, and AddressParser. Avoid words like Manager, Processor, Data, Info in the name of a class. A class name should not be a verb.

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Method names
Methods should have verb or verb phrase names like postPayment

deletePage, or save.
Accessors, mutators, and predicates should be named for their value and prefixed with get, set , and is according to the javabean standard.

Слайд 19

Method Names Should Say What They Do
Date newDate = date.add(5);
Would you

expect this to add five days to the date? Or is it weeks, or hours?
Is the date instance changed or does the function just return a new Date without changing the old one?
You can’t tell from the call what the function does.

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One function – one operation
Functions (aka methods)

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Functions (aka methods)

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F1:Too Many Arguments
Functions should have a small number of arguments. No

argument is best, followed by one, two, and three.
F2: Output Arguments
Output arguments are counterintuitive. Readers expect arguments to be inputs, not outputs. If your function must change the state of something, have it change the state of the object it is called on.

Functions (aka methods)

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F3: Flag Arguments
Boolean arguments loudly declare that the function does more

than one thing. They are confusing and should be eliminated
F4: Dead Function
Methods that are never called should be discarded. Keeping dead code around is wasteful. Don’t be afraid to delete the function. Remember, your source code control system still remembers it.

Functions (aka methods)

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I’ll leave the project when complete all my technical debt

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Code review
Each team member review the code and writing comments/recomendations
It’s

a primary responsibility of TL/Senior at the project
Code have to be understandable by your colleagues (from other teams)
Good news – we have automatic code quality check tools available

Слайд 26

Comments
C1: Inappropriate Information
Change histories(?)
Authors(?)
Date of last update(?)
C2: Obsolete Comment
It is best

not to write a comment that will become obsolete
If you find an obsolete comments – update or erase it ASAP!

Слайд 27

Comments
C3. Redundant Comment
Don’t comment what a code does – I can

read the code for that—keep it DRY
Example 1
i++; // increment i
What about example 2?
/**
* @param sellRequest
* @return
* @throws ManagedComponentException
*/
public SellResponse beginSellItem(SellRequest sellRequest)
throws ManagedComponentException

Слайд 28

Comments
C4: Poorly Written Comment
Comments should say Why or purpose, not how
C5:

Commented-Out Code
Who knows how old it is? Who knows whether or not it’s meaningful? Yet no one will delete it because everyone assumes someone else needs it or has plans for it.

Слайд 29

General
G1: Multiple Languages in One Source File
a Java source file might

contain snippets of XML, HTML, YAML, JavaDoc, English, JavaScript or
in addition to HTML a JSP file might contain Java, a tag library syntax, English comments, Javadocs, XML, JavaScript, and so forth.
The ideal is for a source file to contain one, and only one, language. Realistically, we will probably have to use more than one.

Слайд 30

General
G5: Duplication
Every time you see duplication in the code, it represents

a missed opportunity for abstraction.
Result of copy/paste programming – to separate method
switch/case or if/else chain that appears again and again in various modules, always testing for the same set of conditions – to use polymorphism

Слайд 31

General
G5: Duplication (cont)
modules that have similar algorithms, but that don’t share

similar lines of code – to use Template Method or Strategy design patterns.
Find and eliminate duplication wherever you can!

Слайд 32

General
G6: Code at Wrong Level of Abstraction
Good software design requires that

we separate concepts at different levels and place them in different containers

Слайд 33

General
G7: Base Classes Depending on Their Derivatives
The most common reason for

partitioning concepts into base and derivative classes is so that the higher level base class concepts can be independent of the lower level derivative class concepts.

Слайд 34

General
G9: Dead Code
You find it in the body of an if

statement that checks for a condition that can’t happen. You find it in the catch block of a try that never throws. You find it in little utility methods that are never called or switch/case conditions that never occur.

Слайд 35

General
G11: Inconsistency
If you do something a certain way, do all similar

things in the same way.
If you name a method processVerificationRequest, then use a similar name, such as processDeletionRequest, for the methods that process other kinds of requests.

Слайд 36

General
G23: Prefer Polymorphism to If/Else or Switch/Case
“ONE SWITCH” rule:
There may

be no more than one switch statement for a given type of selection. The cases in that switch statement must create polymorphic objects that take the place of other such switch statements in the rest of the system.

Слайд 37

General
G28: Encapsulate Conditionals
if (shouldBeDeleted(timer))
is preferable to
if (timer.hasExpired() && !timer.isRecurrent())

Слайд 38

General
G29: Avoid Negative Conditionals
if (buffer.shouldCompact())
is preferable to
if (!buffer.shouldNotCompact())

Слайд 39

General
G35: Keep Configurable Data at High Levels

Слайд 40

One more
Clear, not Clever
Don’t be clever, instead be clear
“I never make

stupid mistakes. Only very, very clever ones”
John Peel

Слайд 41

What is “code smell”?
Wiki say:
In computer programming, code smell is any symptom in the source code of

a program that possibly indicates a deeper problem. Code smells are usually not bugs—they are not technically incorrect and don't currently prevent the program from functioning. Instead, they indicate weaknesses in design that may be slowing down development or increasing the risk of bugs or failures in the future.

Слайд 42

The most “popular” code smells

Слайд 43

Bad vs. Clean code
What is the clean code?
What is the bad

code?
Characteristics of quality code
Metrics to measure quality
Ways to identify and build quality

Слайд 44

What do you know now?
What is Code Smell
It’s a feeling or

sense that something is not right in the code
You can’t understand it
Hard to explain
Does some magic
Can we measure it?

Слайд 45

Code quality

Содержание

Tell me, what is a clean code for you?

for (i = 0;i < strlen(line);i++) { short char_code = isupper(line[i])

void CEquation::trio(double array[][rt+1],double alfa[][rt+1]) { for (int L = 0; L

Good vs Bad

How to write beautiful codeThere are two parts to learning craftsmanship:

80% of the lifetime cost of a piece of software goes

Why do we see a bad code?Time: I don't have a

Naming is important

The name should represent the developer’s ideaint d; // time from

The name should represent the developer’s ideapublic List getThem() { List list1

The name should represent the developer’s ideapublic List getFlaggedCells() { List flaggedCells

Use meaningful differencepublic static void copyChars(char a1[], char a2[]) { for (int

Use meaningful namesprivate Date genymdhms; private Date modymdhms;private final String pszqint

Use searchable names#define CFT_CNT 13#define SSIM_CLS_CNT 4096#define PX_BUFF_CNT 10000

Class namesClasses and objects should have noun or noun phrase names

Method namesMethods should have verb or verb phrase names like postPayment

Method Names Should Say What They DoDate newDate = date.add(5);Would you

One function – one operationFunctions (aka methods)

Functions (aka methods)

F1:Too Many ArgumentsFunctions should have a small number of arguments. No

F3: Flag ArgumentsBoolean arguments loudly declare that the function does more

I’ll leave the project when complete all my technical debt

Code review Each team member review the code and writing comments/recomendationsIt’s

CommentsC1: Inappropriate InformationChange histories(?)Authors(?)Date of last update(?)C2: Obsolete CommentIt is best

CommentsC3. Redundant CommentDon’t comment what a code does – I can

CommentsC4: Poorly Written CommentComments should say Why or purpose, not howC5:

GeneralG1: Multiple Languages in One Source Filea Java source file might

GeneralG5: DuplicationEvery time you see duplication in the code, it represents

GeneralG5: Duplication (cont)modules that have similar algorithms, but that don’t share

GeneralG6: Code at Wrong Level of AbstractionGood software design requires that

GeneralG7: Base Classes Depending on Their DerivativesThe most common reason for

GeneralG9: Dead CodeYou find it in the body of an if

GeneralG11: InconsistencyIf you do something a certain way, do all similar

GeneralG23: Prefer Polymorphism to If/Else or Switch/Case“ONE SWITCH” rule: There may

GeneralG28: Encapsulate Conditionals if (shouldBeDeleted(timer)) is preferable to if (timer.hasExpired() && !timer.isRecurrent())

GeneralG29: Avoid Negative Conditionalsif (buffer.shouldCompact())is preferable to if (!buffer.shouldNotCompact())

GeneralG35: Keep Configurable Data at High Levels

One moreClear, not CleverDon’t be clever, instead be clear“I never make

What is “code smell”?Wiki say: In computer programming, code smell is any symptom in the source code of

The most “popular” code smells

Bad vs. Clean codeWhat is the clean code?What is the bad

What do you know now?What is Code SmellIt’s a feeling or

How to improve code quality?

Похожие презентации

How to write beautiful code
There are two parts to learning craftsmanship:

Why do we see a bad code?
Time: I don't have a

The name should represent the developer’s idea
int d; // time from

The name should represent the developer’s idea
public List getThem() {
List list1

The name should represent the developer’s idea
public List getFlaggedCells() {
List flaggedCells

Use meaningful difference
public static void copyChars(char a1[], char a2[]) {
for (int

Use meaningful names
private Date genymdhms;
private Date modymdhms;
private final String pszqint

Use searchable names
#define CFT_CNT 13
#define SSIM_CLS_CNT 4096
#define PX_BUFF_CNT 10000

Class names
Classes and objects should have noun or noun phrase names

Method names
Methods should have verb or verb phrase names like postPayment

Method Names Should Say What They Do
Date newDate = date.add(5);
Would you

One function – one operation
Functions (aka methods)

F1:Too Many Arguments
Functions should have a small number of arguments. No

F3: Flag Arguments
Boolean arguments loudly declare that the function does more

Code review
Each team member review the code and writing comments/recomendations
It’s

Comments
C1: Inappropriate Information
Change histories(?)
Authors(?)
Date of last update(?)
C2: Obsolete Comment
It is best

Comments
C3. Redundant Comment
Don’t comment what a code does – I can

Comments
C4: Poorly Written Comment
Comments should say Why or purpose, not how
C5:

General
G1: Multiple Languages in One Source File
a Java source file might

General
G5: Duplication
Every time you see duplication in the code, it represents

General
G5: Duplication (cont)
modules that have similar algorithms, but that don’t share

General
G6: Code at Wrong Level of Abstraction
Good software design requires that

General
G7: Base Classes Depending on Their Derivatives
The most common reason for

General
G9: Dead Code
You find it in the body of an if

General
G11: Inconsistency
If you do something a certain way, do all similar

General
G23: Prefer Polymorphism to If/Else or Switch/Case
“ONE SWITCH” rule:
There may

General
G28: Encapsulate Conditionals
if (shouldBeDeleted(timer))
is preferable to
if (timer.hasExpired() && !timer.isRecurrent())

General
G29: Avoid Negative Conditionals
if (buffer.shouldCompact())
is preferable to
if (!buffer.shouldNotCompact())

General
G35: Keep Configurable Data at High Levels

One more
Clear, not Clever
Don’t be clever, instead be clear
“I never make

What is “code smell”?
Wiki say:
In computer programming, code smell is any symptom in the source code of

Bad vs. Clean code
What is the clean code?
What is the bad

What do you know now?
What is Code Smell
It’s a feeling or