YAPC::Asia 2014 Talking about Perl::Lint

1. Perl::Lint - Yet Another
Perl Source Code Linter
http://bit.ly/1p5HdSA
@moznion

2. VOTE ME!

3. SEE ALSO
Perlの静的解析入門と
Perlリファクタリングツール
App::PRTのご紹介
@hitode909
!
Day 2, 多目的教室3, 16:00

4. @moznion

5. @moznion
@hitode909

6. Perl::Lint
! https://github.com/moznion/Perl-Lint
https://metacpan.org/release/MOZNION/Perl-
Lint-0.01_01 (<= UNDERDEVELOPMENT!!!)

7. Perl::Lint
! https://github.com/moznion/Perl-Lint
https://metacpan.org/release/MOZNION/Perl-
Lint-0.01_02 (<= UNDERDEVELOPMENT!!!)

8. What is
Perl::Lint?

9. A. Source Code Linter
for Perl

10. Yes, It’s like…
Perl::
http://bit.ly/1l5HrYX

11. Are you using
Perl::Critic? http://bit.ly/1pfMxCW

12. What is
Perl::Critic?

13. A. Source Code Linter
for Perl

14. Wait!!

15. What is
Source Code
Linter???

16. A. Analyzes the
source code and
detects the causes
of bugs

17. Search
and
Destroy
http://bit.ly/1AT3Bl3

18. Concretely…

19. There are five bad things

20. There are five bad things

21. There are five bad things

22. There are five bad things

23. There are five bad things

24. There are five bad things

25. It was fun?

26. Is this what I think it is?

27. It’s just CODE REVIEW?

28. But do you think human
should do the such code
review?

29. Human should work
more creative

30. It seems possible to
check by computer

31. There are five bad things

32. And probably
human overlooks

33. Hard to Understand Code

34. Hard to Understand Code
Destroy!

35. Hard to Understand Code
Easy to review

36. Do you like clean code,
and why?

37. Readable code
!
!
Reviewable code

38. Readable code
≒
!
!
Reviewable code

39. => Maintainable!!

40. Maintainable code
will be growing up
along maintainable

41. Humans can focus on
creative work

42. Okay,
Make maintainable code
by computer!

43. And then source code
linter was appeared
(1979 for C)

44. Now;
js-lint, find-bugs,
rubocop, etc…

45. And language
processors:
Go, Scala and etc.

46. Does Perl have?

48. Perl::Critic is awesome!

49. Perl::Critic checks
the code conform
to PBP style or not

50. Benefit to analyze
code by computer

51. He don’t grumble

52. He is
inexhaustible

53. He don’t take a mistake

54. He is fast
(in many cases)

55. And can automation

56. Cost of human: HIGH
!
Cost of computer: LOW

57. Cost of human: HIGH
!
Cost of computer: LOW
Good!!

58. Got it.

59. But…
If there is Perl::Critic,
Is Perl::Lint don’t need?

60. Perl::Critic is awesome
but a little slow

61. In large project,
It takes 3 minutes
to run only Perl::Critic

62. How do you spend in
meantime?

63. Coffee?
How do you spend in
meantime?

64. Coffee?
Chat?
How do you spend in
meantime?

65. Coffee?
Nap? Chat?
How do you spend in
meantime?

66. Coffee?
Swing Copters?
Nap? Chat?
How do you spend in
meantime?

67. Life is too short,
so let’s accelerate!!

68. Rate [num/sec]
100
75
50
25
0
97
18
Perl::Critic Perl::Lint

69. Rate [num/sec]
100
75
About 50
400% increase
25
0
97
18
Perl::Critic Perl::Lint

70. Yeah!!!!
I'll show you all my tricks

71. A little break

72. Background that led to
the development

73. This project receive
TPF grant

74. Do you know
TPF grant?

75. Nozaki-san and
Maki-san (@lestrrat-san)
are people in a high
position of TPF grant

76. Maki-san「日本人がトップになっ
たのに日本から1つもProposal出な
いのちょっとアレじゃない？」▼
me「そうですなあ」▼
Maki-san「moznion出してよ」▼
me「！！！！！」▼

77. Time flies everything
goes…

79. Perl::Lint!!!!

80. Let’s apply!!!

81. Return to our subject…

82. How do we do
static analyzing for Perl?

84. Enough!

85. Joke :p

86. Two major methods
- Evaluate Token
- Evaluate AST

87. Two major methods
- Evaluate Token
- Evaluate AST

88. Tools - PPI - Compiler::Lexer

89. Tools - PPI - Compiler::Lexer

90. What is Compiler::Lexer?

91. *Very Fast* tokenizer
made of C++

92. Compiler::Lexer is fast
⇛ Perl::Lint is fast!

93. And others:
Compiler::Parser,
C::CodeGenerator::LLVM,
etc…
@goccy54++

94. Example of tokens
that is generated by
Compiler::Lexer

95. my $foo;

96. my $foo;

97. Points

98. Use these tokens
to analyze

100. Enough!

101. Architecture of Perl::Lint

102. Top Level
+args
+site_policies
+lint
+lint_string
Policies
+evaluate
1
Filters
+filter
1
1 .. *
1 .. *

103. Simple and Easy!

104. Policies

105. Each policies are
isolated

106. Easy to make
your own policy

107. Samples

108. *** CAUTION ***
A lot of bad
code are here.
Close your eyes.

109. @P::L::P::Miscellanea::ProhibitTies

110. @P::L::P::Miscellanea::ProhibitTies
Check type

111. @P::L::P::Miscellanea::ProhibitTies
Check data

113. アッ

114. Feature of
Implementation
and Bad Know-hows

115. Use C-Style for()

116. Use C-Style for()
But PBP prohibit it!!

117. Use List::Util::any
instead of grep

118. Don’t use regex,
compare by eq in series

119. Or use hash
…

120. Function calling
is almost gone.

121. Use simple parts
e.g. raw-bless, POPO

122. Filtering mechanism

123. Perl::Critic’s
default rule system
is a bit difficult…

124. Yes, I know,
perlcriticrc can
adjust them.
But too much hustle

125. Perl::Lint checks
the all of policies
as default

126. And you can filter
any policies as you like

127. Filter by `ignore`

128. Filter by `filter`

129. Yes, of course
you can deny
the all of policies :)

130. You can define
your own filter

131. e.g.

132. And Perl::Lint provides
default policies

135. For Perl::Critic users ;)

136. These are features
of Perl::Lint

137. But installation is such a
hassle!

138. Perl::Lint
Playground
http://perl-lint.moznion.net

139. You can try!

140. Meaning to publish
Playground

141. It makes easy to get
feedback

142. Motivation ➚

143. Publish the Playground
is looking good!

144. Future works

145. Implement the all of
policies…

146. ## no lint

147. Module for testing
(Like a Test::Perl::Critic)

148. Cooperate with GitHub
(Like a Coveralls)

149. Inject the result
into code as TODO
comment
(inspired by rubocop)

150. As you see,
Perl::Lint is
under development

151. SEGV, ABRT, etc…

152. I’m looking for
contributors!

153. DEMO

154. Any Questions?