The World Runs on Bad Software

Transcript

1. Brandon Keepers
   Lone Star Ruby Conference V
   August 12, 2011
   BAD
   the world runs on
   software
   Ordered List
   

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3. @bkeepers
   I

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4. opensoul.org
   I

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6. group therapy
   

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9. pride
   

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10. craftsman
    

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11. art
    

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12. I

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13. get.harmonyapp.com
    

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14. get.gaug.es
    

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15. speakerdeck.com
    

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17. I — GOOD CODE!
    

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18. not perfect
    

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19. :(
    

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20. HAS NOT
    IMPLODED
    

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21. HAS NOT
    IMPLODED yet
    ^
    

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22. RUNS
    

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23. in spite of
    

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24. because of
    

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25. bad software
    

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26. pragmatism
    perfection
    

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27. What is good software?
    How does it go bad?
    How do we build better software?
    

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28. good software
    

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29. “
    Good software meets the
    present objective at an
    acceptable cost without
    incurring an unacceptable
    amount of future risk.
    

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30. adequacy
    

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31. !mediocrity
    

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32. objective
    

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33. software
    !=
    code
    

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34. “
    Zach Dennis
    Mutually Human Software
    People fail to realize that
    quality is merely a property of
    the code that exists, not the
    reason for its existence.
    

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35. users don’t care
    

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36. “
    Scott Berkun
    We’re frustrated most in
    life by things that come
    close to our deepest
    needs, but don’t deliver.
    

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37. cost
    

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38. “
    Ray Yeargin
    Virtually all of the cost of
    software development is,
    directly and indirectly, the
    cost of design.
    

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39. Production
    almost zero of
    

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40. $$$$
    

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41. $$$
    

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42. $$
    

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43. $
    

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45. risk
    

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46. !science
    

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47. ‑Risk
    ‐Cost
    

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48. What is good software?
    How does it go bad?
    How do we build better software?
    

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49. entropy
    

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50. “
    The Pragmatic Programmer
    While software development
    is immune from almost all
    physical laws, entropy hits
    us hard.
    

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51. why?
    

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52. software is
    malleable
    

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54. software is
    complex
    

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55. rake stats
    

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56. 2.5 million parts
    

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58. software is
    immature
    

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60. software is
    opaque
    

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61. software is
    durable
    

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62. View Slide

63. What is good software?
    How does it go bad?
    How do we build better software?
    

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64. better software?
    how do we build
    

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65. talk to your users
    

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66. automated testing
    

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67. insurance policy
    

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68. automation
    computers are good at
    

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70. DRY
    

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72. refactoring
    small, incremental
    

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73. What is good software?
    How does it go bad?
    How do we build better software?
    

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74. Examples
    

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75. method_missing
    

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76. class NilClass
    def method_missing(method, *args)
    nil
    end
    end
    

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77. >> nil.foo.bar
    => nil
    >> nil + 5
    => nil
    >> 5 + nil
    TypeError: coerce must return [x, y]
    

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79. performance
    maintenance
    

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80. def to_xml(options={})
    root_tag = options.fetch(:root, 'game')
    instruct = options[:skip_instruct] ? '' : XML_INSTRUCT
    # …
    # gather up a bunch of variables
    # …
    <<-EOF
    #{instruct}
    <#{root_tag}>
    #{id}
    #{current_move_user_id}
    current-move-user-id>
    #{created_by_user_id}
    created-by-user-id>
    0
    #{is_matchmaking}
    #{was_matchmaking}matchmaking>
    #{moves_count}
    #{random_seed}
    

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81. #{instruct}
    <#{root_tag}>
    #{id}
    #{current_move_user_id}
    current-move-user-id>
    #{created_by_user_id}
    created-by-user-id>
    0
    #{is_matchmaking}
    #{was_matchmaking}matchmaking>
    #{moves_count}
    #{random_seed}
    #{client_version}
    #{created_at.try(:xmlschema)}
    created-at>
    #{users_xml}
    #{current_user_xml}
    #{moves_xml}
    #{chats_xml}
    #{root_tag}>
    EOF
    end
    

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82. commit fa779d9c2d1214e43ff497f386b51ebf3708346e
    Author: Brandon Keepers
    Date: Wed Sep 22 17:08:38 2010 -0400
    First attempt at getting embedded callbacks working
    

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83. def create_or_update
    run_callbacks(:before_save)
    if result = super
    run_callbacks(:after_save)
    end
    result
    end
    Rails 2
    

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84. def create_or_update
    run_callbacks(:save) { super }
    end
    Rails 3
    

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85. def run_callbacks(kind, options={}, &block)
    self.embedded_associations.each do |association|
    self.send(association.name).run_callbacks(
    kind, options, &block
    )
    end
    end
    

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86. def run_callbacks(callback, &block)
    embedded_docs = []
    embedded_associations.each do |association|
    embedded_docs += association.target
    end
    block = embedded_docs.inject(block) do |chain, doc|
    if doc.class.respond_to?("_#{callback}_callbacks")
    lambda { doc.run_callbacks(callback, &chain) }
    else
    chain
    end
    end
    super callback, &block
    end
    

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87. SystemStackError: stack level too deep
    from mongo_mapper/plugins/embedded_callbacks.rb:23:in `run_callbacks'
    from activesupport-3.0.9/lib/active_support/callbacks.rb:414:in
    `_run_create_callbacks'
    from activesupport-3.0.9/lib/active_support/callbacks.rb:94:in `send'
    from activesupport-3.0.9/lib/active_support/callbacks.rb:94:in
    `run_callbacks'
    from mongo_mapper/plugins/embedded_callbacks.rb:28:in `run_callbacks'
    from mongo_mapper/plugins/embedded_callbacks.rb:23:in `run_callbacks'
    

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88. now what?
    

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89. pragmatic
    

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90. software is design
    

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91. embrace constraints
    

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92. engineering is design
    

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93. craftsmanship is design
    

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94. “
    Glen Vanderburg
    Sometimes you have to move
    ahead with weak evidence and
    weak conclusions because you
    don't have time to prove them.
    

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95. opportunity costs
    

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96. be pragmatic
    

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98. “
    Ed Yourdon
    You can discipline yourself to write
    software that's good enough—good
    enough for your users, for future
    maintainers, for your own peace of
    mind. You'll find that you are more
    productive and your users are happier.
    

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99. Ordered List
    Thank you!
    [email protected]
    Brandon Keepers
    Lone Star Ruby Conference V
    August 12, 2011
    @bkeepers
    http://spkr8.com/t/7829
    

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100. Credits
     Power lines - http://www.flickr.com/photos/viamoi/3339707547/
     House of cards - http://www.flickr.com/photos/gibbons/2294374741/
     Dentists office - http://www.flickr.com/photos/cmdrcord/4996672560/
     Broken chair - http://www.flickr.com/photos/gorbould/3004789912/
     Schematics - http://www.flickr.com/photos/nicklockey/4547935355/
     Engineers - http://www.flickr.com/photos/seattlemunicipalarchives/4818952324/
     Black box - http://goldberg.berkeley.edu/art/big-images/
     

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