1
00:00:00,000 --> 00:00:03,690
You now have a class with attributes, a constructor

2
00:00:03,750 --> 00:00:07,470
and methods, great. But this is just a structure

3
00:00:07,470 --> 00:00:10,710
inside your program. If you run your code now like

4
00:00:10,710 --> 00:00:12,990
this, well, nothing is going to happen. So

5
00:00:12,990 --> 00:00:17,610
actually, let's do that. Let's do Run, and code, so

6
00:00:17,610 --> 00:00:21,330
oop_example. Well, this works. But we have

7
00:00:21,360 --> 00:00:25,050
nothing. Okay? If I add, let's say, an add here,

8
00:00:25,050 --> 00:00:27,720
[No audio]

9
00:00:27,720 --> 00:00:32,850
print, say, test, okay, with zero indentation, I

10
00:00:32,850 --> 00:00:37,200
run it, and I see test. Okay, so test is executed

11
00:00:37,470 --> 00:00:41,340
the class, well, nothing happened. So just as we

12
00:00:41,340 --> 00:00:43,530
have seen with a function, well, a function is

13
00:00:43,530 --> 00:00:46,170
just a bunch of code that you need to call in your

14
00:00:46,170 --> 00:00:50,370
program, otherwise, it won't do anything. And this

15
00:00:50,370 --> 00:00:53,010
is the same for classes, we need to create an

16
00:00:53,010 --> 00:00:56,670
object or also called an instance of the class,

17
00:00:56,820 --> 00:00:59,730
so we can use the class functionalities. So let's

18
00:00:59,730 --> 00:01:03,030
actually do this, I'm going to create an object

19
00:01:03,030 --> 00:01:07,680
here. And I'm going to call it my_robot is equal

20
00:01:07,680 --> 00:01:12,210
to Robot like this. And I open the parenthesis, and

21
00:01:12,210 --> 00:01:14,880
as you can see, so I have the suggestions from

22
00:01:15,180 --> 00:01:19,080
PyCharm. So this, those here are actually the

23
00:01:19,080 --> 00:01:23,340
parameters from the constructor here. So we need

24
00:01:23,340 --> 00:01:26,160
to provide the name and the version_number. So

25
00:01:26,160 --> 00:01:32,010
let's say our Robot is named R2D2. And the

26
00:01:32,010 --> 00:01:35,450
version_number is, so here, well, for the version_number,

27
00:01:35,450 --> 00:01:37,710
you could use an integer, float, string,

28
00:01:37,710 --> 00:01:40,170
whatever. And I'm just going to keep it very

29
00:01:40,170 --> 00:01:43,110
simple, and say this is the version two of the

30
00:01:43,410 --> 00:01:47,730
Robot. So now I have my_robot. Okay, so to

31
00:01:47,730 --> 00:01:51,540
create an object, you call the constructor simply

32
00:01:51,540 --> 00:01:55,470
by as you can see, writing the name of the class,

33
00:01:55,560 --> 00:01:58,920
and then parentheses. And if there are any

34
00:01:58,920 --> 00:02:02,910
parameters here after self, you then need to

35
00:02:02,910 --> 00:02:07,346
provide the parameters. So name, and version_number,

36
00:02:07,346 --> 00:02:09,449
what's going to happen is that the name

37
00:02:09,479 --> 00:02:12,210
here, this is going to be a local variable, that

38
00:02:12,210 --> 00:02:16,170
is going to be assigned in the self.name, so in

39
00:02:16,170 --> 00:02:18,390
the attribute of the class, and the same for

40
00:02:18,390 --> 00:02:21,960
version_number, okay. So after we call this, this

41
00:02:21,960 --> 00:02:24,690
is going to be self dot name, this is going to be

42
00:02:24,690 --> 00:02:27,750
self.version_number in the class. And now what

43
00:02:27,750 --> 00:02:30,450
I can do, so here, it's not going to do anything,

44
00:02:30,450 --> 00:02:33,690
just create the Robot with the constructor. And

45
00:02:33,690 --> 00:02:39,956
then what I can do, for example, is my_robot.say_hi,

46
00:02:39,956 --> 00:02:45,453
okay, and then my_robot.init_hardware,

47
00:02:45,453 --> 00:02:52,440
and then my_robot.print_info. Okay,

48
00:02:52,440 --> 00:02:55,170
so as you can see here, so the self, the first

49
00:02:55,170 --> 00:02:57,480
parameter is actually not something that you have

50
00:02:57,480 --> 00:03:01,170
to add here, the self refers to the object. So if

51
00:03:01,170 --> 00:03:03,480
you have this, it means you have to call the

52
00:03:03,480 --> 00:03:08,635
method directly from the object. So my_robot.say_hi,

53
00:03:08,635 --> 00:03:13,800
it's going simply to call this and pass

54
00:03:13,890 --> 00:03:17,160
the my_robot object as the self here, as simple

55
00:03:17,160 --> 00:03:19,560
as that. And then if you have any other parameter,

56
00:03:19,560 --> 00:03:22,560
you call the parameter. But otherwise, that's it.

57
00:03:23,100 --> 00:03:27,540
So I'm going to run the test. So I create an

58
00:03:27,600 --> 00:03:30,300
object, and then I call the different functions or

59
00:03:30,300 --> 00:03:33,780
the different methods. And then I can also get

60
00:03:33,810 --> 00:03:37,590
access. So let's say print, I can get also access

61
00:03:37,590 --> 00:03:43,170
to my_robot, for example, dot, let's say name. So

62
00:03:43,170 --> 00:03:47,010
you can get access of the attributes, okay, of the

63
00:03:47,010 --> 00:03:51,090
class, also directly with my_robot.name. Let's

64
00:03:51,120 --> 00:03:55,980
run this now. And let's see what we have. So we

65
00:03:55,980 --> 00:03:59,363
first create the Robot. And then you can see say_hi

66
00:03:59,363 --> 00:04:02,370
hi is going to say Hello, my name is R2D2

67
00:04:02,370 --> 00:04:06,551
ready to help. Actually, I'm just going to add these here.

68
00:04:08,280 --> 00:04:11,910
And then Init hardware, okay, because we call it init_hardware method.

69
00:04:11,910 --> 00:04:14,790
And then you can see we call print_info,

70
00:04:14,790 --> 00:04:17,100
which is going to call say_hi, another time,

71
00:04:17,100 --> 00:04:19,829
so hello again. And then Version number:,

72
00:04:19,860 --> 00:04:22,980
Temperature, which is from the print_info method.

73
00:04:23,250 --> 00:04:26,790
And then we'll print my_robot.name, which is

74
00:04:26,790 --> 00:04:29,010
going to print R2D2, which is the

75
00:04:29,370 --> 00:04:32,430
attribute of the class directly. Okay, nice. Now

76
00:04:32,430 --> 00:04:35,280
we have an object created from the Robot class.

77
00:04:35,430 --> 00:04:38,790
But actually, we can create as many objects as we

78
00:04:38,790 --> 00:04:41,700
want from the class. Okay? Just as when you create

79
00:04:41,700 --> 00:04:44,130
a function, you can just call it as many times as

80
00:04:44,130 --> 00:04:46,920
you want, here, I'm going to create another Robot,

81
00:04:46,920 --> 00:04:52,200
let's say my_robot2. Okay. And then my_robot2

82
00:04:52,200 --> 00:04:55,950
is going to be Robot, also. So the constructor and

83
00:04:55,950 --> 00:05:00,298
I'm going to give a different name. Let's say C3PO,

84
00:05:00,298 --> 00:05:02,280
and this is going to be Version

85
00:05:02,280 --> 00:05:07,680
one of the Robot. And I'm going to remove that

86
00:05:08,160 --> 00:05:10,405
and remove that. And I'm simply going to do my

87
00:05:10,405 --> 00:05:15,574
my_robot.print_info and my_robot2.print_info.

88
00:05:15,574 --> 00:05:17,940
Okay, so I call the same method from

89
00:05:17,970 --> 00:05:21,420
two different objects, which have two different

90
00:05:21,420 --> 00:05:25,500
sets of attributes. Okay, I run this, and you can

91
00:05:25,500 --> 00:05:28,680
see, Hello, my name is R2D2, Version

92
00:05:28,680 --> 00:05:33,530
number: 2, Temperature 25. And then my name is C3PO,

93
00:05:33,530 --> 00:05:36,480
and Version number: 1. Okay, so here

94
00:05:36,480 --> 00:05:40,170
we have two complete independent and different

95
00:05:40,230 --> 00:05:42,840
objects, okay, using the same class, the same

96
00:05:42,840 --> 00:05:45,630
blueprint, but that have a different set of

97
00:05:45,660 --> 00:05:48,120
attributes, okay, and you can use them

98
00:05:48,180 --> 00:05:51,600
independently. So to recap, in order to create an

99
00:05:51,600 --> 00:05:54,090
object from a class, you need to write the name of

100
00:05:54,090 --> 00:05:58,110
the class first, to call the constructor and pass

101
00:05:58,110 --> 00:06:01,530
the required parameters to initialize attributes.

102
00:06:01,920 --> 00:06:04,410
Then from that object, you can call the class

103
00:06:04,410 --> 00:06:07,680
methods. You can also create multiple objects from

104
00:06:07,680 --> 00:06:11,130
the same class, and each object will have its own

105
00:06:11,160 --> 00:06:15,000
internal mechanism and attributes independent from

106
00:06:15,030 --> 00:06:17,174
the other objects.