The document discusses design patterns from Java to Ruby. It covers singleton, observer, iterator, factory patterns and differences between Java and Ruby implementations. In Ruby, classes are objects and patterns like singleton, observer and iterator are built-in while factory pattern leverages dynamic typing by passing a class name as a string.

1. Design Pattern
-- from Java to Ruby
Richard
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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
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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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