Design Patterns in Ruby

I gave talk on Design Patterns in Ruby at 'Pune Ruby Users Group' meeting on 6th July, 2013. Here are the code snippets https://gist.github.com/anildigital/5939892

Transcript

1. Design Patterns in Ruby
   Anil Wadghule Ruby hacker
   Sunday, 7 July 13
   

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2. What are Design Patterns?
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3. What are Design Patterns?
   Design Patterns are nothing but decent pre-loaded
   solutions to common problems
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4. What are Design Patterns?
   They are worth knowing because they are solutions to
   common problems
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5. Are ‘Design Patterns’ restricted to certain
   programming languages?
   NO! They are programming language independent.
   They can be implemented in any programming
   language
   Most OOP-specific design patterns may be irrelevant to functional languages
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6. Design Patterns book by Gang of Four
   It made Design Patterns popular
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7. Design Patterns categories
   Creational patterns (Singleton, Builder etc)
   Structural patterns (Adapter, Composite, Proxy etc)
   Behavioral patterns (Command, Strategy, Observer etc)
   Architectural patterns (MVC - Model View Controller etc)
   Concurrency patterns (Reactor, Thread pool etc)
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8. Design Patterns we will see
   are
   Template Method
   Strategy
   Proxy
   Composite
   Adapter
   Decorator
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9. Template Method
   Document
   def render
   render_title(@title)
   render_footer(@author)
   ...
   end
   HTML Document
   Text Document
   def render_title(t)
   end
   def render_author(a)
   end
   def render_title(t)
   end
   def render_author(a)
   end
   Template Method
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10. Strategy
    Document
    def initialize(renderer)
    @renderer = renderer
    end
    def render
    @renderer.render(self)
    end
    HTMLRenderer
    TextRenderer
    def render(doc)
    puts doc.title
    puts “By #{doc.author}”
    end
    def render(doc)
    ...
    end
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11. Strategy
    Separate out the change
    Composition NOT inheritance
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12. Proxy
    Document
    def render(doc)
    puts doc.title
    puts “By #{doc.author}”
    end
    ProxyDoc
    def render
    if allowed?
    @doc.render
    end
    end
    client
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13. Adapter
    Document
    def render
    end
    Adapter
    def print
    @doc.render
    end
    client
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14. Composite
    Document
    def render
    end
    Composite
    def render
    @subdocs.each do |s|
    s.render
    end
    end
    client
    Document
    def render
    end
    Document
    def render
    end
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15. Decorator
    Document
    def render
    end
    Decorator
    def to_japanese
    translate(@doc.paragraphs)
    end
    def render
    @doc.render + “do awesome”
    end
    client
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16. Recommended Book
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17. References
    http://en.wikipedia.org/wiki/Software_design_pattern
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18. Thanks!
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19. Questions?
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20. @anildigital on twitter
    anildigital@gmail.com
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