Design patterns in Ruby

Design Patterns
in

Ruby

@russolsen 1

Wednesday, July 25, 12

Th ird

& Me!
4


(magma)

edward.og

5

FORTRAN Pascal

BASIC
C
C++
Python Java
Ruby
Clojure
6


Design Patterns:
3 Things in 1

7


Philosophy of

Good Design
8


Common Problems

Common Solutions
9


Some
Common Solutions

10


More
@#$&
Documents!
11


Templates
&

Strategies

12


Document
def render
render_title(@title)
render_author(@author)
...
end

PlainDocument HtmlDocument
def render_title(t) def render_title(t)
end end

def render_author(a) def render_author(a)
end end

Template Method 13


PlainRender
def render(doc)
puts doc.title
Document puts “By #{doc.author}”
...
end
def render
@renderer.render(self)
end

HtmlRenderer
def render(doc)
...
end

Strategy 14


Separate
Out
Change
15


Think Interface
NOT
Implementation
16


Composition
NOT
Inheritance
17


Delegate!

18


Five
In
Five!
19


Client

“Stand In” “Real Object”

Do something with @real Do real stuff

Stand In Meta Pattern 20

What If
You
Need Control?
21


Proxy!
22


Client

ProxyDoc Document
def render def render(doc)
if allowed? puts doc.title
@doc.render puts “By #{doc.author}”
end ...
end end

Proxy 23


What If
You
Need More?
24


Decorate!
25


Client

Decorator Document

def to_japanese
translate(@doc.paragraphs)
end

def render
@doc.render
end

Decorator 26


What If
You
Need Less?
27


Facade!
28


Client
EnterpriseDoc

Facade
10,000 Complex methods
def render
@ent_doc.complex_stuff()
end

Facade 29


What If
You Need
Different?
30


Adapt!
31


Client

Adapter Document

def print def render
@doc.render ...
end end

Adapter 32


What If
You Need

Little Bits?
33


Compose!
34


Document
Client

Document
CompositeDoc
def render
@subdocs.each do |s|
s.render
end
end Document

Composite 35


Design Patterns are
nothing but decent
pre-loaded solutions to
common problems.

36


They are worth your time
because of they are
solutions, but also
because they are decent.

37


russ@russolsen.com
@russolsen

thinkrelevance.com

38


Design patterns in Ruby

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