Fear Me Not

This was a lightning talk given by my wife, Dana Gray, at MountainWest RubyConf 2009. She encouraged programmers to shed their fear of regular expressions and learn to use them properly.

Transcript

1. Don’t worry, there are only four.
   Fear Me Not
   Tips for Conquering Regular Expressions
   

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2. Contrary to popular
   opinion, Regex
   doesn’t have to make
   you feel like this =>
   Popular Opinion
   

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3. Do I need help?
   

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4. Do I need help?
   My name is Dana and I like Regular Expressions
   

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5. Do I need help?
   My name is Dana and I like Regular Expressions
   It’s been two days since my last Regular
   Expression
   

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6. When is the end
   really the end?
   

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7. When is the end
   really the end?
   data[/\d+$/] # => "10"
   

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8. When is the end
   really the end?
   data[/\d+$/] # => "10" attendance =
   "Women = 10
   Men = 215
   Total = 225
   "
   

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9. When is the end
   really the end?
   data[/\d+$/] # => "10"
   data[/\d+\z/] # => nil
   attendance =
   "Women = 10
   Men = 215
   Total = 225
   "
   

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10. When is the end
    really the end?
    data[/\d+$/] # => "10"
    data[/\d+\z/] # => nil
    data[/\d+\Z/] # => "225"
    attendance =
    "Women = 10
    Men = 215
    Total = 225
    "
    

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11. In Ruby dummy talk, please
    

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12. In Ruby dummy talk, please
    Symbol WTF?
    

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13. In Ruby dummy talk, please
    Symbol WTF?
    ^ Matches the beginning of any line - 100 lines
    means 100 matches
    

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14. In Ruby dummy talk, please
    Symbol WTF?
    ^ Matches the beginning of any line - 100 lines
    means 100 matches
    \A Matches the beginning of the string - at most 1
    match
    

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15. In Ruby dummy talk, please
    Symbol WTF?
    ^ Matches the beginning of any line - 100 lines
    means 100 matches
    \A Matches the beginning of the string - at most 1
    match
    $ Matches the end of any line - 100 lines means
    100 matches
    

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16. In Ruby dummy talk, please
    Symbol WTF?
    ^ Matches the beginning of any line - 100 lines
    means 100 matches
    \A Matches the beginning of the string - at most 1
    match
    $ Matches the end of any line - 100 lines means
    100 matches
    \z Matches the end of the string - at most 1
    match
    

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17. In Ruby dummy talk, please
    Symbol WTF?
    ^ Matches the beginning of any line - 100 lines
    means 100 matches
    \A Matches the beginning of the string - at most 1
    match
    $ Matches the end of any line - 100 lines means
    100 matches
    \z Matches the end of the string - at most 1
    match
    \Z Matches the end of the string or just before
    the last \n - at most 1 match
    

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18. Getting exactly
    what I want
    

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19. Getting exactly
    what I want
    ["Gray is a great color.",
    "I like gray things.",
    "I’m hung up on a guy named Gray.",
    "He lives in Castle Grayskull."]
    

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20. Getting exactly
    what I want
    ["Gray is a great color.",
    "I like gray things.",
    "I’m hung up on a guy named Gray.",
    "He lives in Castle Grayskull."]
    /(\W|\A)gray(\W|\Z)/i
    

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21. Getting exactly
    what I want
    ["Gray is a great color.",
    "I like gray things.",
    "I’m hung up on a guy named Gray.",
    "He lives in Castle Grayskull."]
    /(\W|\A)gray(\W|\Z)/i
    /\bGray\b/i
    

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22. Getting exactly
    what I want
    ["Gray is a great color.",
    "I like gray things.",
    "I’m hung up on a guy named Gray.",
    "He lives in Castle Grayskull."]
    /(\W|\A)gray(\W|\Z)/i
    /\bGray\b/i
    ["Gray is a great color.",
    "I like gray things.",
    "I’m hung up on a guy named Gray."]
    

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23. Let’s discuss our differences
    What’s the difference
    between this - ( ... )
    !
    !
    and this? - (?: ... )
    

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24. Let’s discuss our differences
    What’s the difference
    between this - ( ... )
    !
    !
    and this? - (?: ... )
    phone = "123-456-7890"
    phone =~ /\A(\d+)-(\d+)-(\d+)\z/
    puts "#{$1}#{$2}#{$3}"
    !
    # >> 1234567890
    

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25. Let’s discuss our differences
    What’s the difference
    between this - ( ... )
    !
    !
    and this? - (?: ... )
    phone = "123-456-7890"
    phone =~ /\A(\d+)-(\d+)-(\d+)\z/
    puts "#{$1}#{$2}#{$3}"
    !
    # >> 1234567890
    name = "James Edward Gray II"
    name =~ /\A(\w+)(?:\s\w+)?\s(\w+)/
    puts "#{$1} #{$2}"
    !
    # >> James Gray
    

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26. When you can’t make up
    your mind
    Sometimes you just
    can’t decide exactly
    what you want
    

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27. When you can’t make up
    your mind
    Sometimes you just
    can’t decide exactly
    what you want
    /(42|41|40|...)/
    

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28. When you can’t make up
    your mind
    Sometimes you just
    can’t decide exactly
    what you want
    /(42|41|40|...)/
    /[0-9]/
    

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29. When you can’t make up
    your mind
    Sometimes you just
    can’t decide exactly
    what you want
    /(42|41|40|...)/
    /[0-9]/
    /[1-3]?[0-9]/
    

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30. When you can’t make up
    your mind
    Sometimes you just
    can’t decide exactly
    what you want
    /(42|41|40|...)/
    /[0-9]/
    /[1-3]?[0-9]/
    /(4[0-2]|[1-3]?[0-9])/
    

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32. "Fear Regex".sub!(/\AFear\b/, "Embrace")
    

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