Post on 28-May-2015
description
Design Patterns in RubyAnil Wadghule Ruby hacker
Sunday, 7 July 13
What are Design Patterns?
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What are Design Patterns?
Design Patterns are nothing but decent pre-loaded solutions to common problems
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What are Design Patterns?
They are worth knowing because they are solutions to common problems
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Are ‘Design Patterns’ restricted to certain programming languages?
NO! They are programming language independent.
They can be implemented in any programming languageMost OOP-specific design patterns may be irrelevant to functional languages
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Design Patterns book by Gang of Four
It made Design Patterns popular
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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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Design Patterns we will see are
Template Method
Strategy
Proxy
Composite
Adapter
Decorator
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Template MethodDocument
def renderrender_title(@title)render_footer(@author) ...
end
HTML DocumentText 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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Strategy
Document
def initialize(renderer) @renderer = rendererend
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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Strategy
Separate out the change
Composition NOT inheritance
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Proxy
Document
def render(doc) puts doc.title puts “By #{doc.author}”end
ProxyDoc
def render if allowed?
@doc.render endend
client
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Adapter
Document
def renderend
Adapter
def print @doc.renderend
client
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CompositeDocument
def renderend
Composite
def render @subdocs.each do |s|
s.render endend
client
Document
def renderend
Document
def renderend
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Decorator
Document
def renderend
Decorator
def to_japanese translate(@doc.paragraphs)end
def render @doc.render + “do awesome”end
client
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Recommended Book
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References
http://en.wikipedia.org/wiki/Software_design_pattern
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Thanks!
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Questions?
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@anildigital on twitter
anildigital@gmail.com
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