Wow Code, Such Read! (NR Ruby UnConf)

Abstract:
When we learn to code, that usually means learning how to *write* code. However in practice, we spend a lot of time *reading* code instead! It’s the way we find answers to questions about how things work. Reading code efficiently is therefore a very valuable skill. This talk will cover how Ruby developers can improve this skill, with tips for comprehending and debugging code faster. We'll also take a look at how you’d go one level deeper and read Ruby’s own source code, even if you don’t know much about C!

This talk was presented at an internal Ruby unconf at New Relic.
Blog post: http://kwugirl.blogspot.com/2016/05/wow-code-such-read.html

Transcript

1. @kwugirl Wow Code, Such Read! KWu Ruby Agent Engineer amaze understand so power
2. @kwugirl the goal: get better at reading code
3. be fearless in diving into code you don’t know Edmond Lau theeffectiveengineer.com
4. @kwugirl
5. @kwugirl 10,000 hours
6. @kwugirl 10,000 hours 250 weeks
7. @kwugirl 10,000 hours 250 weeks ~5 years!
8. @kwugirl productive struggling
9. @kwugirl 2. remember your question 3. enlist help 1. see the code
10. @kwugirl the problem
11. @kwugirl the problem connection.execute("EXPLAIN #{query}")
12. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
13. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
14. @kwugirl { :sql=>
 "SELECT \"blogs\".* FROM \"blogs\" WHERE \"blogs\". \"id\" = $1 LIMIT 1", … :binds=> [[#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn: 0x007fd13a879e58 @array=false, @cast_type=#<ActiveRecord::ConnectionAdapters::PostgreS QL::OID::Integer:0x007fd13a87afd8 @limit=nil, @precision=nil, @range=-2147483648...2147483648, @scale=nil>,…,42]] } ActiveSupport::Notifications.subscribe 'sql.active_record'
15. @kwugirl { :sql=>
 "SELECT \"blogs\".* FROM \"blogs\" WHERE \"blogs\". \"id\" = $1 LIMIT 1", … :binds=> [[#<ActiveRecord::ConnectionAdapters::PostgreSQLColumn: 0x007fd13a879e58 @array=false, @cast_type=#<ActiveRecord::ConnectionAdapters::PostgreS QL::OID::Integer:0x007fd13a87afd8 @limit=nil, @precision=nil, @range=-2147483648...2147483648, @scale=nil>,…,42]] } ActiveSupport::Notifications.subscribe 'sql.active_record'
16. @kwugirl 2. remember your question 3. enlist help 1. see the code
17. @kwugirl
18. @kwugirl $ cd src/
19. @kwugirl $ cd src/ $ git clone git@github.com:rails/rails.git
 $ cd rails/
20. @kwugirl $ cd src/ $ git clone git@github.com:rails/rails.git
 $ cd rails/ $ git checkout v4.2.0
21. @kwugirl # Gemfile gem 'rails', '4.2.0'
22. @kwugirl # Gemfile # gem 'rails', '4.2.0' gem 'rails', :path => '../../src/rails'
23. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
24. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
25. @kwugirl @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } def log(sql, name = "SQL", binds = [], statement_name = nil) # active_record/connection_adapters/abstract_adapter.rb
26. @kwugirl def log(sql, name = "SQL", binds = [], statement_name = nil) @instrumenter.instrument( "sql.active_record", :sql => sql, :name => name, :connection_id => object_id, :statement_name => statement_name, :binds => binds) { yield } puts "====== HELLO IS IT ME YOU'RE LOOKING FOR?!!?? ======" # active_record/connection_adapters/abstract_adapter.rb
27. @kwugirl git blame (can be) your friend
28. @kwugirl 2. remember your question 3. enlist help 1. see the code
29. @kwugirl don’t get lost
30. @kwugirl don’t get lost learn one thing at a time
31. @kwugirl don’t get lost learn one thing at a time what are your unknowns?
32. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
33. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
34. @kwugirl the problem connection.execute("EXPLAIN #{query}") SELECT "blogs".* FROM "blogs" WHERE "blogs"."id" = $1 LIMIT 1 with
35. @kwugirl 2. remember your question 3. enlist help 1. see the code
36. @kwugirl pair programming
37. @kwugirl pair programming ?????????? ?????????? ??????????
38. @kwugirl
39. @kwugirl What are you looking for?
40. @kwugirl What are you looking for? Why?
41. @kwugirl What are you looking for? Why? How did you know to look there?
42. @kwugirl Kernel#caller
43. @kwugirl active_record/connection_adapters/postgresql_adapter.rb:601:in `exec_cache' active_record/connection_adapters/postgresql_adapter.rb:585:in `execute_and_clear' active_record/connection_adapters/postgresql/database_statements.rb:161:in `exec_query' active_record/connection_adapters/abstract/database_statements.rb:341:in `select' active_record/connection_adapters/abstract/database_statements.rb:37:in `select_all' active_record/connection_adapters/abstract/query_cache.rb:70:in `select_all' active_record/querying.rb:39:in `find_by_sql' active_record/relation.rb:639:in `exec_queries' active_record/relation.rb:514:in `load' active_record/relation.rb:243:in `to_a' active_record/relation.rb:617:in `pretty_print' Kernel#caller
44. @kwugirl Method#source_location
45. @kwugirl Method#source_location $ bundle exec rails console
46. @kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location
47. @kwugirl Method#source_location $ bundle exec rails console irb(main):001:0> method(:try).source_location => ["/…/active_support/core_ext/object/try.rb", 62]
48. @kwugirl method_defined? RubyTapas #439 “Method Search”
49. @kwugirl method_defined? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp, Hash, Array, String] RubyTapas #439 “Method Search”
50. @kwugirl method_defined? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp, Hash, Array, String] RubyTapas #439 “Method Search”
51. @kwugirl method_defined? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp, Hash, Array, String] RubyTapas #439 “Method Search”
52. @kwugirl method_defined? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp, Hash, Array, String] RubyTapas #439 “Method Search”
53. @kwugirl method_defined? $ ObjectSpace.each_object(Class).select{|c| c.singleton_class.method_defined?(:try_convert) } => [File, IO, Regexp, Hash, Array, String] RubyTapas #439 “Method Search”
54. @kwugirl 2. remember your question 3. enlist help 1. see the code
55. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
56. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
57. @kwugirl the solution connection.exec_query("EXPLAIN #{statement.sql}", "Explain #{statement.name}", statement.binds) wow beauty wonder
58. @kwugirl success!!1!one!!
59. @kwugirl success!!1!one!! $1
60. @kwugirl success!!1!one!! $1 }Explain plan
61. @kwugirl success!!1!one!! released in 3.15.2 $1 }Explain plan
62. @kwugirl reading ruby source
63. @kwugirl gentle intro
64. @kwugirl gentle intro
65. @kwugirl which files?
66. @kwugirl which files?
67. @kwugirl github.com/ruby/ruby
68. @kwugirl github.com/ruby/ruby “trunk” not “master”
69. @kwugirl pretty flat directory
70. @kwugirl pretty flat directory
71. @kwugirl std library in lib/
72. @kwugirl extension.rdoc
73. @kwugirl parse.y
74. @kwugirl other helpful points
75. @kwugirl other helpful points rb_
76. @kwugirl other helpful points rb_ regex search with ^ to find method definition
77. @kwugirl other helpful points rb_ regex search with ^ to find method definition comments
78. @kwugirl bugs.ruby-lang.org
79. @kwugirl resources
80. @kwugirl resources readingcodegood.com
81. @kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby”
82. @kwugirl resources readingcodegood.com schneems' talk “Dissecting Ruby with Ruby” schneems.com/2016/01/25/ruby-debugging-magic- cheat-sheet.html
 tenderlovemaking.com/2016/02/05/i-am-a-puts- debuggerer.html
83. @kwugirl resources
84. @kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro”
85. @kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro” Hsing-Hui Hsu’s talk “Time flies like an arrow, fruit flies like a banana”
86. @kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro” Hsing-Hui Hsu’s talk “Time flies like an arrow, fruit flies like a banana” Ruby Under A Microscope
87. @kwugirl resources Jason Clark’s talk “GDB: A Gentle Intro” Hsing-Hui Hsu’s talk “Time flies like an arrow, fruit flies like a banana” Ruby Under A Microscope Definitive Guide to Ruby’s C API: 
 https://silverhammermba.github.io/emberb/c/
88. @kwugirl Julia Evans jvns.ca
89. @kwugirl Net::HTTP is maybe 2000 lines of code, not including comments. Julia Evans jvns.ca
90. @kwugirl Net::HTTP is maybe 2000 lines of code, not including comments. It has ~1000 lines of comments… Julia Evans jvns.ca
91. @kwugirl Net::HTTP is maybe 2000 lines of code, not including comments. It has ~1000 lines of comments… I can read 2000 lines of code, Julia Evans jvns.ca
92. @kwugirl Net::HTTP is maybe 2000 lines of code, not including comments. It has ~1000 lines of comments… I can read 2000 lines of code, mostly! Julia Evans jvns.ca
93. @kwugirl doge The White Rabbit, Alice in Wonderland sad Keanu pear/pair programming Lionel Richie + Where’s Waldo !!1!one!! the “!1” phenomenon breadfish Slurms MacKenzie, Futurama