The document discusses objects across different programming paradigms like HTML, CSS, JavaScript, Ruby. It explains that objects have both behavior and state. Behavior can change state. While HTML, CSS don't fully exhibit object-oriented properties, JavaScript and Ruby are truly object-oriented - everything is an object. In Ruby, literals create new objects but some values like numbers are singleton objects. Object IDs help identify singleton objects. Objects provide consistency and help represent real-world entities.

1. Objects, Objects
Everywhere
Mike Pack
@zombidev

2. Let’s Talk Objects
Behavior
+
State

3. Let’s Talk Objects
Behavior
I’m a person, what can I do?
Walk
Talk
Eat
Could also be defined as:
Move Legs
Move Lips
Ingest Food

4. Let’s Talk Objects
Behavior
Level of abstraction matters!
Behavioral abstraction varies per domain.

5. Let’s Talk Objects
State
I’m a person, who am I currently?
Mike Pack
Male
Brown
Therefore, I have attributes:
Name
Gender
Hair Color

6. Let’s Talk Objects
State
States change
When I’m 70, my attributes might be:
Mike Pack
Male
Grey

7. Let’s Talk Objects
Behavior changes too!
I just learned to jump, now my behavior is:
Walk
Talk
Eat
Jump

8. Let’s Talk Objects
Behavior
+
State

9. HTML
<div id=”name”>
Mike
</div>
Is this an object?

10. Attribute
HTML Name
<div id=”name”>
Mike
</div>
Is this an object?

11. Attribute
HTML Name
<div id=”name”>
Mike
State
</div>
Is this an object?

12. Attribute
HTML Name
<div id=”name”>
Mike the beef?
Where’s State
</div>
Is this an object?

13. Attribute
HTML Name
<div id=”name”>
Mike behavior?
Where’s the State
</div>
Is this an object?

14. HTML
<div id=”name”
onclick=”...”>
Mike
</div>
Is this an object?

15. Attribute
HTML Name
<div id=”name”
onclick=”...”>
Mike Behavior!
</div> State
Is this an object?

16. HTML
HTML is object oriented
(albeit, not for purist)
HTML does not exhibit other properties of an OO systems:
- Inheritance
- Polymorphism
- etc

17. HTML
Don’t use onclick=”...”
However, without onclick, HTML does not exhibit behavior.

18. CSS
a{
color: red;
}
Is this an object?

19. CSS
Attribute
a{ Name
color: red;
}
Is this an object?

20. CSS
Attribute
a{ Name
color: red;
} State
Is this an object?

21. CSS
Attribute
a{ Name
color:the beef?
Where’s red;
} State
Is this an object?

22. CSS
a{
color: red;
&:hover {
color: blue;
}
}
Is this an object?

23. Attribute CSS
Name a {
color: red; Behavior!
&:hover {
color: blue;
}
State
}
Is this an object?

24. CSS
a{
Behavior color: red; State
&:hover { Change
color: blue;
}
}
Behavior changes state.

25. CSS
CSS is object oriented
(not for purist)
CSS does not exhibit other properties of an OO systems:
- Inheritance
- Polymorphism
- etc

26. JavaScript
var book = {
title: “The Art of
War”
};
Is this an object?

27. Attribute
Name
JavaScript
var book = {
title: “The Art of
War”
};
Is this an object?

28. Attribute
Name
JavaScript
var book = {
title: “The Art of
War” State
};
Is this an object?

29. Attribute
Name
JavaScript
var book = {
title: “The Art of
Where’s the beef?
War” State
};
Is this an object?

30. Attribute
Name
JavaScript
var book = {
title: “The Art of
Where’s the beef?
It’sWar”
implicit! State
};
Is this an object?

31. JavaScript
var book = {
title: “The Art of War”,
constructor: function() {...},
hasOwnProperty: function() {...},
...
};
Implicit behavior.

32. JavaScript
JavaScript is object oriented
(of course)

33. JavaScript
It’s not entirely object oriented
JavaScript has primitives, too.

34. JavaScript
If it’s an object, typeof knows
typeof {} === ‘object’ //=> true

35. JavaScript
Integers are not objects
typeof 1 === ‘object’ //=> false

36. JavaScript
undefined is not an object
typeof undefined === ‘object’ //=> false

37. JavaScript
Literals are not always primitives
typeof [] === ‘object’ //=> true

38. JavaScript
typeof might not return object
typeof true === ‘object’ //=> false
typeof true === ‘boolean’ //=> true
But booleans are objects!
new Boolean(1).valueOf() === true //=> true

39. JavaScript
Careful, typeof can bite
typeof null === ‘object’ //=> true
new Null() //=> error

40. Ruby
1
Is this an object?

41. Ruby State
(accessor)
1
1.real #=> 1
Is this an object?

42. Ruby State
(accessor)
1
1.real #=> 1
1 + 1 #=> 2
Is this an object?

43. Ruby State
1 (accessor)
1.real #=> 1
Behavior 1 + 1 #=> 2
1.+(1) #=> 2
Is this an object?

44. Ruby
Ruby is object oriented

45. Ruby
Everything is an object

46. Ruby
Literal arrays are new objects
[].object_id #=> 70318249770140
[].object_id #=> 70318249594160

47. Ruby
Literal strings are new objects
‘slurpy’.object_id #=> 70318249561400
‘slurpy’.object_id #=> 70318249500340

48. Ruby
Literal hashes are new objects
{}.object_id #=> 7019206373870
{}.object_id #=> 70192063701240

49. Ruby
Literal regexs are new objects
//.object_id #=> 70192063385520
//.object_id #=> 70192067965040

50. Ruby
Literal ranges are new objects
(1..2).object_id #=> 70192067946460
(1..2).object_id #=> 70192067921120

51. Ruby
Not everything creates a new
object
Ruby has singleton objects (objects instantiated once).

52. Ruby
nil is a singleton
nil.object_id #=> 4
nil.object_id #=> 4

53. Ruby
booleans are singletons
false.object_id #=> 0
false.object_id #=> 0
true.object_id #=> 2
true.object_id #=> 2

54. Ruby
Numbers are singletons
1.object_id #=> 3
1.object_id #=> 3

55. Ruby
um s
xn
Fi Numbers are singletons
1.object_id #=> 3
1.object_id #=> 3

56. Ruby
Bignums are not singletons
4611686018427387904.object_id #=>
70192063730740
4611686018427387904.object_id #=>
70192063508580

57. Ruby
Bignums are not singletons
4611686018427387904.object_id #=>
70192063730740
4611686018427387904.object_id #=>
70192063508580
Why 4611686018427387904?

58. bytes to store
Ruby integer
bytes = 0.size #=> 8

59. bytes to store
Ruby integer
bytes = 0.size #=> 8
8 bits per byte
bits = bytes * 8 #=> 64
64 bit machine

60. bytes to store
Ruby integer
bytes = 0.size #=> 8
8 bits per byte
bits = bytes * 8 #=> 64
64 bit machine
1 bit for sign
+ 1 bit for Ruby
2 ** (bits - 2) #=>
4611686018427387904

61. Ruby
4611686018427387904
Bignum
Different objects.
4611686018427387904 - 1
Fixnum
Singleton object.

62. Ruby
Why does nil have object_id of 4?
1 have object_id of 3?
true have object_id of 2?

63. Ruby
Because Matz says so
false.object_id #=> 0
0.object_id #=> 1
true.object_id #=> 2
1.object_id #=> 3
nil.object_id #=> 4
2.object_id #=> 5

64. Ruby
Find by object_id
ObjectSpace._id2ref(0) #=> false
ObjectSpace._id2ref(1) #=> 0
ObjectSpace._id2ref(2) #=> true
ObjectSpace._id2ref(3) #=> 1
ObjectSpace._id2ref(4) #=> nil
ObjectSpace._id2ref(5) #=> 2
ObjectSpace._id2ref(6) #=> error
ObjectSpace._id2ref(7) #=> 3
ObjectSpace._id2ref(8) #=> error

65. Ruby
Negative object_ids
-1.object_id #=> -1
-2.object_id #=> -3
-3.object_id #=> -5

66. Objects.useful? # => true

67. Objects.useful? # => true
Consistent modeling across the stack.

68. Objects.useful? # => true
Helpful in representing the real world.

69. Objects.useful? # => true
Fun and expressive.

70. Thanks!
@zombidev