The Elements of Style in Programming (WebCamp Zagreb 2015)

Slide deck from my talk at WebCamp Zagreb 2015.

Transcript

1. The Elements of Style in Programming by Bozhidar Batsov
2. Dobar dan Zagrebe!
3. Божидар
4. Božidar
7. I’m an Emacs fanatic
8. bbatsov
10. Sasha, our beloved leader/CTO
12. @bbatsov
14. Why am I here?
16. size=2 start=0 c=['Н', 'Н' ,'Н' ,'Н' ,'Н','Н','Н','Н','Н','Н','Н','Н','Н','Н'] code_dictionary=Array.new() begin_size_code_dictionary=Array.new() end_string=String.new() code_dictionary=c.uniq.to_a decode_dictionary=c.uniq.to_a for i in 0...code_dictionary.size begin_size_code_dictionary[i]=i end c.size.times{ if !code_dictionary.include?(c[start,size].to_s)#Comparation code_dictionary.push(c[start,size].to_s.chomp) start=start+(code_dictionary.last.size)/2-1 size=2 else size+=1; end } end_code=Array.new(code_dictionary.size) for i in begin_size_code_dictionary.size...code_dictionary.size end_code[i]=code_dictionary.index(code_dictionary[i].chop.chop)+1 end_string+=code_dictionary[i].chop.chop end govnokod.ru
17. Languages are hard
19. Basic usage of a language is easy
20. Pipl mast trast as
21. "I was day after 
 yesterday
 in Hungary"
22. The correct usage of a language is hard
23. The effective usage of a language is very hard
24. not really
25. try 10 years
26. http://norvig.com/21-days.html Teach Yourself Programming in Ten Years Peter Norvig
30. Use the active voice.
31. My first visit to Zagreb will always be remembered by me. lame
32. I shall always remember my first visit to Zagreb. legit
33. The word personally is often unnecessary.
34. Personally, I love Emacs.
35. A style guide • a curated set of (supposedly) good practices • spares you the process of making trivial decisions • allows you to focus on the actual problems • simple and concise
36. Style guides aren’t a replacement for thinking
37. Programs must be written for people to read, and only incidentally for machines to execute. — Hal Abelson
38. Similar rules apply to natural and programming languages
40. English
41. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum. Chapter I
42. LOREM IPSUM DOLOR SIT AMET, CONSECTETUR ADIPISCING ELIT, SED DO EIUSMOD TEMPOR INCIDIDUNT UT LABORE ET DOLORE MAGNA ALIQUA. UT ENIM AD MINIM VENIAM, QUIS NOSTRUD EXERCITATION ULLAMCO LABORIS NISI UT ALIQUIP EX EA COMMODO CONSEQUAT. DUIS AUTE IRURE DOLOR IN REPREHENDERIT IN VOLUPTATE VELIT ESSE CILLUM DOLORE EU FUGIAT NULLA PARIATUR. EXCEPTEUR SINT OCCAECAT CUPIDATAT NON PROIDENT, SUNT IN CULPA QUI OFFICIA DESERUNT MOLLIT ANIM ID EST LABORUM. LOREM IPSUM DOLOR SIT AMET, CONSECTETUR ADIPISCING ELIT, SED DO EIUSMOD TEMPOR INCIDIDUNT UT LABORE ET DOLORE MAGNA ALIQUA. UT ENIM AD MINIM VENIAM, QUIS NOSTRUD EXERCITATION ULLAMCO LABORIS NISI UT ALIQUIP EX EA COMMODO CONSEQUAT. DUIS AUTE IRURE DOLOR IN REPREHENDERIT IN VOLUPTATE VELIT ESSE CILLUM DOLORE EU FUGIAT NULLA PARIATUR. EXCEPTEUR SINT OCCAECAT CUPIDATAT NON PROIDENT, SUNT IN CULPA QUI OFFICIA DESERUNT MOLLIT ANIM ID EST LABORUM. chapter i
43. Hrvatski
44. Trebaju nam promjene prema otkrivanju i održavanju perspektive razvoja i napretka. Naša koalicija najavljuje promjene – promjene koje će oživjeti gospodarstvo kao podlogu razvitka, koje će teret reformi ravnomjernije podijeliti između bogatih i siromašnih, koje će omogućiti odgovornu, funkcionalnu i poštenu upravu, koje će racionalizirati potrošnju i javni rashod, a osigurati standard građana, koje će uvesti pravo zajednice na dio dobiti koju pojedinci izvlače ekstraprofitom, pretvarajući tuđi rad u svoju imovinu. 
 Mi najavljujemo promjenu prirode hrvatskoga kapitalizma i konačni odmak od prakse kapitalizma perifernoga, nekontroliranog, pa i nezakonitog profita, bogaćenja na štetu nacionalnih interesa i podcjenjivanja i odbacivanja prava rada i radnika. Naše promjene ne vode prema slabljenju države, nego prema jačanju uloge odgovorne države, a istodobno jačanju uloge njezinih građana. Poglavlje 1
45. TREBAJU NAM PROMJENE PREMA OTKRIVANJU I ODRŽAVANJU PERSPEKTIVE RAZVOJA I NAPRETKA. NAŠA KOALICIJA NAJAVLJUJE PROMJENE – PROMJENE KOJE ĆE OŽIVJETI GOSPODARSTVO KAO PODLOGU RAZVITKA, KOJE ĆE TERET REFORMI RAVNOMJERNIJE PODIJELITI IZMEĐU BOGATIH I SIROMAŠNIH, KOJE ĆE OMOGUĆITI ODGOVORNU, FUNKCIONALNU I POŠTENU UPRAVU, KOJE ĆE RACIONALIZIRATI POTROŠNJU I JAVNI RASHOD, A OSIGURATI STANDARD GRAĐANA, KOJE ĆE UVESTI PRAVO ZAJEDNICE NA DIO DOBITI KOJU POJEDINCI IZVLAČE EKSTRAPROFITOM, PRETVARAJUĆI TUĐI RAD U SVOJU IMOVINU. pOgLaVljE 1 MI NAJAVLJUJEMO PROMJENU PRIRODE HRVATSKOGA KAPITALIZMA I KONAČNI ODMAK OD PRAKSE KAPITALIZMA PERIFERNOGA, NEKONTROLIRANOG, PA I NEZAKONITOG PROFITA, B O G A Ć E N J A N A Š T E T U N A C I O N A L N I H I N T E R E S A I PODCJENJIVANJA I ODBACIVANJA PRAVA RADA I RADNIKA. SADAŠNJA VLAST SAMO JE ZAŠTITNIK I JAMAC NASTAVKA TAKVE PRAKSE. NAŠE PROMJENE NE VODE PREMA SLABLJENJU DRŽAVE, NEGO PREMA JAČANJU ULOGE ODGOVORNE DRŽAVE
46. Ruby
47. def some_method do_something do_more do_more end
48. def some_method do_something do_more do_more end
49. sum = 1 + 2 a, b = 1, 2 [1, 2, 3].each { |e| puts e } class FooError < StandardError; end
50. sum=1+2 a,b=1,2 [1,2,3].each{|e|puts e} class FooError<StandardError;end
51. English
52. Form possessive singular of nouns by adding ’s.
53. Bozhidar’s talk Batman’s batclaw Emacs’s magic
54. Ruby
55. Form predicate method names by adding “?”.
56. even? completed? batman?
57. English
58. Make the paragraph the unit of composition.
59. Ruby
60. Make the method the unit of composition.
61. English
62. Omit needless words.
63. he is a man who
64. Her story is a strange one.
65. Ruby
66. Omit needless words.
67. if some_condition then # body omitted end
68. def some_method # ... return result end
69. English
70. farther further
71. Do we have to go much farther?
72. I decided to pursue the subject further.
73. Ruby
74. == === equal? eql?
75. An approach to style
76. Be consistent
77. English
78. The user should update his config accordingly. They should also check…
79. The user should update his config accordingly. They should also check…
80. Ruby
81. def something coll coll.collect(&:ala) end def something2(coll) coll.map { |x| x.bala } end
82. Be clear
83. Hrvatski
84. HP
85. Hladno Pivo
86. DNK
87. Da Nije Komšijin
88. USKOK
89. Ured za suzbijanje korupcije i organiziranog kriminaliteta
90. Ruby
91. $:
92. $LOAD_PATH
93. $;
94. $FIELD_SEPARATOR
95. $*
96. $ARGV
97. '%d %d' % [20, 10]
98. sprintf('%d %d', 20, 10)
99. sprintf( '%{first} %{second}', first: 20, second: 10 )
100. format('%{first} %{second}', first: 20, second: 10)
101. Ruby is optimized for programmer happiness
102. Ruby is a huge language
103. Making the “right” decisions is hard
104. puts "Hello, WebCamp!" puts "Hello, WebCamp!" puts "Hello, WebCamp!"
105. for i in 1..3 puts "Hello, WebCamp!" end
106. 3.times do puts "Hello, WebCamp!" end
107. result = [] names.each do |word| result << name.upcase end
108. names.map { |name| name.upcase }
109. names.map(&:upcase)
113. 56 simple rules
114. Format a program to help the reader understand it.
115. Write clearly -- don't be too clever.
116. def user_signed_in? !!@current_user end def user_signed_in? !@current_user.nil? end
117. Don't sacrifice clarity for small gains in efficiency.
118. i = 1 res = 0 while i <= 10 res += i i += 1 end
119. (1..10).reduce(:+)
120. (N * (N + 1)) / 2
121. (10 * (10 + 1)) / 2
122. Don't diddle code to make it faster -- find a better algorithm.
123. •Make it right before you make it faster. •Make it fail-safe before you make it faster. •Make it clear before you make it faster.
124. Instrument your programs. Measure before making efficiency changes.
125. Use variable names that mean something.
126. a s l
127. age sex location
128. age_over_18?
129. adult?
130. Don’t repeat yourself.
131. Parenthesize to avoid ambiguity.
132. x || y && z
133. x || (y && z)
134. Keep the code & its comments in sync.
135. # This method does bla bla bla. # It returns an array of results. def bla_bla_bla res = Set.new # ... res end
136. bla_bla_bla[0] # => Boom Boom Pow bla_bla_bla.uniq # => Kaboom!
137. //private instance variable for storing age public static int age;
138. //private instance variable for storing age public static int age;
139. //private instance variable for storing age public static int age;
140. Don’t repeat the code in the comments.
141. # increment counter by 1 counter += 1
142. Don’t comment shitty code — fix it.
143. // // Dear maintainer: // // Once you are done trying to 'optimize' this routine, // and have realized what a terrible mistake that was, // please increment the following counter as a warning // to the next guy: // // total_hours_wasted_here = 42 //
144. Fuck this shit!!!
145. Style guides for programming languages
146. Python
147. PEP-8 http://legacy.python.org/dev/peps/pep-0008/
148. Java
149. Sun Style Guide http://www.oracle.com/technetwork/java/codeconvtoc-136057.html
150. Google Style Guide https://google-styleguide.googlecode.com/svn/trunk/javaguide.html
151. Go
152. Effective Go https://golang.org/doc/effective_go.html
153. gofmt
155. Airbnb Style Guide https://github.com/airbnb/javascript
156. Google Style Guide https://google-styleguide.googlecode.com/svn/trunk/javascriptguide.xml
158. PHP FIG Coding Style Guide http://www.php-fig.org/psr/psr-1/ http://www.php-fig.org/psr/psr-2/
160. Ruby Style Guide https://github.com/bbatsov/ruby-style-guide
162. Clojure Style Guide https://github.com/bbatsov/clojure-style-guide
163. Languages are always evolving
164. Good style practices are evolving as well
165. { :batman => 'Bruce', :superman => 'Clark', :zorro => 'Diego', :catwoman => 'Selina' }
166. { batman: 'Bruce', superman: 'Clark', zorro: 'Diego', catwoman: 'Selina' }
167. Style consistency is of paramount importance
168. Community Personal Project Company
169. Community Project Company
170. Style separates the good from the great
171. Felina
172. One more thing…