1. Analysing code quality
Linters and Static Analysis

2. Hello!
Weverton Timoteo
@wevtimoteo

3. “
Any fool can write code that a
computer can understand.
Good programmers write code that
humans can understand.
– Martin Fowler

4. How Do You Define
“Good Code” ?

5. maintainability?

6. Efficiency Modularity Elegance
What's the first thing that comes to your
mind?
Proper design
decision

7. Error rate
Comprehensibility
Reviewability
Debugging
External quality
Modifiability
Development time
You write readable code because it helps
other people to read your code
“
Code Complete, Steve McConnel

8. Simplicity
is it about the number of lines?

9. Readability
comments, conventions, naming

10. Modularity
its all about reusability

11. Layering
attention to the boundaries of each layer

12. Design
plan before build

13. Efficiency
too many connections?

14. Elegance
solve problems with proper solutions

15. Clarity
do you really know what you have to do?

16. Which one matters
most?

17. Balance

18. How to achieve
this?

19. is a tool that analyzes source code to flag
programming errors, bugs, stylistic errors,
and suspicious constructs
- Wikipedia
What is a linter?
“

20. Lexer and Parser
● Lexer: converts the statements in code into various
categories of like keywords, constants, variable in a
sentence and produce token
● Parser: takes the tokens produced by the lexer and tries
to determine whether these statements are semantically
correct

21. Packages - Std lib
scanner token astparser

22. Abstract Syntax Tree (AST)

23. Abstract Syntax Tree (AST)

24. Abstract Syntax Tree (AST)

25. Abstract Syntax Tree (AST)

26. Abstract Syntax Tree (AST)

27. Homoiconicity
● The code used to express a program is
written using the data structures of
that language
● The Lisp family languages (Common
Lisp, Scheme, Clojure, etc)
● Code is Data, Data is Code

29. ● gofmt - Must have for every project
● goimports - Additionally to gofmt, checks unused imports
● unindent - Report code that is unnecessarily indented
Code Formatting

30. gofmt -s (Simplify)

31. goimports

32. ● abcgo - ABC metrics for Go source code.
● gocyclo - Computes and checks the cyclomatic
complexity of functions.
● splint - It finds any functions that are too long or have too
many parameters or results.
Code Complexity

33. ABC Metrics - Calculate Score
● Assignment count when:
=, *=, /=, %=, +=, <<=, >>=,
&=, ^=
++, --
● Branch count when:
Function call
● Condition count when:
<, >, <=, >=, ==, !=
else, case

34. ABC Metrics (abcgo)

35. ● GoLint - Golint is a linter for Go source code
● revive - Drop-in replacement of golint
● go-namecheck - helps you to maintain variable/field
naming conventions inside your project
● lll - Line length linter, used to enforce line length in files
Style and Patterns Checking

36. golint

37. Revive
● Allows to enable, disable, configure
rules using a TOML file
● Allows disabling a specific rule or
the entire linter for a file or a range
of lines
● Provides multiple formatters which
let us customize the output

38. Revive - Configuration

40. Revive - Custom Rule

41. Revive - Custom Rule

42. Revive - Custom Rule

43. ● govet - checks correctness: a vet check identifies real or
potential bugs that could cause incorrect compilation or
execution
● badtime - Badtime is a Golang linter that detects
inappropriate usage of the time.Time struct.
● safesql - Static analysis tool for Golang that protects
against SQL injections.
Bugs

44. govet

45. ● Performance
● Unused code
● Reports
● Outdated packages
● Code without tests (no coverage)
● Magic number detector
What else?

46. How should I start?

47. Thanks!
Any questions?
Which linters are you
using?
Tell me! @wevtimoteo

48. References
● Code Complete: A Practical Handbook of Software Construction
● Effective Go
● golang/lint Repository
● SourceLevel: Team Metrics and Automated Code Review
● How do you define “Good Code”?
● Awesome Go Linters
● scanner Package
● Basic AST Manipulation in Go
● Internal vs External Software Quality

49. References
● Code Complete: A Practical Handbook of Software Construction
● Lexical Scanning in Go - Rob Pike