1. Design Pattern
-- from Java to Ruby
Richard
Ekohe
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2. Why use Design Pattern
 For reuse
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3. Why use Design Pattern
 For communication
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4. Why use Design Pattern
Define a Node interface, all of leaf nodes and
internal nodes should implements the
interface, internal nodes has a list that
 For communication includes other internal nodes and leaf nodes
and it can add and remove sub-nodes. But
leaf node can’t have add sub-node method.
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5. Why use Design Pattern
Define a Node interface, all of leaf nodes and
internal nodes should implements the
interface, internal nodes has a list that
 For communication includes other internal nodes and leaf nodes
and it can add and remove sub-nodes. But
leaf node can’t have add sub-node method.
www.ekohe.com
Web Development & Graphic Design
China Ruby on Rails Development - Rails Consulting - Rails Services - Merb - Offshore Web Development

6. Why use Design Pattern
Define a Node interface, all of leaf nodes and
internal nodes should implements the
interface, internal nodes has a list that
 For communication includes other internal nodes and leaf nodes
and it can add and remove sub-nodes. But
leaf node can’t have add sub-node method.
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7. Why use Design Pattern
 For communication
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8. Why use Design Pattern
 For communication
Composite
Pattern
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9. Why use Design Pattern
 For communication
Composite
Pattern
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10. Difference from java to ruby
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11. Difference from java to ruby
 Classes are Objects
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12. Difference from java to ruby
 Classes are Objects
 Messages, not function call
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13. Difference from java to ruby
 Classes are Objects
 Messages, not function call
 Duck Typing
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14. Difference from java to ruby
 Classes are Objects
 Messages, not function call
 Duck Typing
 Mixin
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15. Singleton Pattern
 ensures a class has only one instance, and
provides a global point of access to it
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16. Singleton Pattern
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17. Singleton Pattern
You are my
only wife
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18. Singleton Pattern
You are my
You are my
only husband
only wife
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19. Singleton Pattern -- java
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20. Singleton Pattern -- java
 Eager loading
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21. Singleton Pattern -- java
 Eager loading
 Lazy loading
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22. Singleton Pattern -- ruby
 Ruby built-in singleton
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23. Singleton Pattern -- ruby
 Ruby built-in singleton
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24. www.ekohe.com
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25. www.ekohe.com
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26. www.ekohe.com
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27. www.ekohe.com
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28. www.ekohe.com
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29. Ruby for Design Pattern
 Built-in (Singleton)
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30. Observer Pattern
 defines a one-to-many dependency between
objects so that when one object changes state,
all of its dependents are notified and updated
automatically
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31. Observer Pattern
Subscribe
Temperature
Detector
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32. Observer Pattern
Subscribe
Temprature
Temperature
changed
Detector
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33. Observer Pattern
Notify Notify
Subscribe
Temprature
Temperature
changed
Detector
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34. Observer Pattern -- java
 Define interface by yourself
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35. Observer Pattern -- java
 Define interface by yourself
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36. Observer Pattern -- java
 Define interface by yourself
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37. Observer Pattern -- java
 Define interface by yourself
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38. Observer Pattern -- java
 Define interface by yourself
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39. Observer Pattern -- java
 Define interface by yourself
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40. Observer Pattern -- java
 Java built-in observer
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41. Observer Pattern -- java
 Java built-in observer
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42. Observer Pattern -- ruby
 Ruby built-in observer
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43. Observer Pattern -- ruby
 Ruby built-in observer
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44. Observer Pattern -- ruby
 Ruby built-in observer
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45. www.ekohe.com
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46. www.ekohe.com
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47. www.ekohe.com
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48. Ruby for Design Pattern
 Built-in (Singleton, Observer)
 Mixin
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49. Iterator Pattern
 provides a way to access the elements of an
aggregate object sequentially without exposing
its underlying representation
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50. Iterator Pattern
Count 1 2 3 10
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51. Iterator Pattern -- java
 Java built-in Iterator and mock Iterator
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52. Iterator Pattern -- java
 Java built-in Iterator and mock Iterator
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53. Iterator Pattern -- java
 Java built-in Iterator and mock Iterator
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54. Iterator Pattern -- java
 Java built-in Iterator and mock Iterator
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55. Iterator Pattern -- ruby
 Nothing, just .each
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56. Iterator Pattern -- ruby
 Nothing, just .each
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57. Iterator Pattern -- ruby
 Nothing, just .each
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58. Ruby for Design Pattern
 Built-in (Singleton, Observer, Iterator)
 Mixin
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59. Simple Factory Pattern
 returns an instance of one of several possible
classes, depending on the data provided to it.
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60. Simple Factory Pattern
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61. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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62. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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63. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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64. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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65. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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66. Simple Factory Pattern -- java
 Compare with String, a lot of if/else
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67. Simple Factory Pattern -- ruby
 Classes are Objects
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68. Simple Factory Pattern -- ruby
 Classes are Objects
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69. Simple Factory Pattern -- ruby
 Classes are Objects
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70. Simple Factory Pattern -- ruby
 Classes are Objects
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71. Ruby for Design Pattern
 Built-in (Singleton, Observer, Iterator)‫‏‬
 Mixin
 Classes are Objects
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72. Command Pattern
 encapsulates a request as an object, thereby
letting you parameterize clients with different
requests, queue or log requests, and support
undoable operations.
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73. Command Pattern
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74. Command Pattern -- java
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75. Command Pattern -- java
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76. Command Pattern -- java
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77. Command Pattern -- java
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78. Command Pattern -- java
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79. Command Pattern -- ruby
 Proc
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80. Command Pattern -- ruby
 Proc
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81. Ruby for Design Pattern
 Built-in (Singleton, Observer, Iterator)‫‏‬
 Mixin
 Classes are Objects
 Proc
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82. Other Design Patterns
Make use of ruby advantage
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83. Ruby's Principle
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84. Ruby's Principle
 DRY – Don't Repeat Yourself
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85. Ruby's Principle
 DRY – Don't Repeat Yourself
 Convention Over Configuration
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86. Resources
 Design Pattern – Elements of Reusable Object-Oriented Software
Erich Gamma, Richard Helm, Ralph Johnson, John Vlissides
 Head First Design Pattern
Kathy Sierra, Bert Bates
 Design Pattern in Ruby
Russ Olsen
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87. Q&A
happy to discuss and fix my mistakes
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