1
00:00:00,300 --> 00:00:06,450
So will come back again in this list and we're going to talk about protocols so protocols as the name

2
00:00:06,450 --> 00:00:15,200
implies are essentially a set of instructions and a class or a structure on ENM will adopt to that protocol

3
00:00:15,240 --> 00:00:21,830
meaning whatever rules are there in the protocol that class or data structure that Inform should follow.

4
00:00:21,990 --> 00:00:23,640
So why is this useful for us.

5
00:00:23,640 --> 00:00:29,820
It is useful for us in a situation where we have different classes that we want all of them to conform

6
00:00:29,820 --> 00:00:31,740
to a certain set of things.

7
00:00:31,740 --> 00:00:37,920
For instance they all have showed a certain number of primitives or they all should implement a certain

8
00:00:37,920 --> 00:00:39,060
function.

9
00:00:39,060 --> 00:00:44,500
Now what is important to understand about protocols is that they don't actually contain any logic.

10
00:00:44,580 --> 00:00:50,530
They just have the declaration of the methods or attributes they don't understand what is going to happen

11
00:00:50,530 --> 00:00:51,100
to be taught.

12
00:00:51,090 --> 00:00:53,420
And they don't have the implementation of it.

13
00:00:53,460 --> 00:01:00,240
So in Turin you could have protocols that are adopted by different classes but each class does its own

14
00:01:00,240 --> 00:01:01,570
thing on their mettle.

15
00:01:01,710 --> 00:01:08,350
So the school head into a school and going I start a new project I'm going to make it of the types with

16
00:01:08,450 --> 00:01:17,850
and is going to be protocol protocols with particular protocols the right protocol swift

17
00:01:20,510 --> 00:01:21,490
animal protocols.

18
00:01:21,500 --> 00:01:30,200
If I'm going to do this I'm going to say I have one protocol and that protocol is going to be let's

19
00:01:30,200 --> 00:01:32,780
call our protocol admissible.

20
00:01:33,260 --> 00:01:33,620
All right.

21
00:01:33,620 --> 00:01:41,310
It means anyone who conforms to this is acceptable or is admissible not nine.

22
00:01:41,400 --> 00:01:47,270
And we are working on that same application that we have discussed multiple times which is about a real

23
00:01:47,270 --> 00:01:49,840
estate property listing application.

24
00:01:49,970 --> 00:01:53,390
So in the application we have a clause for property.

25
00:01:53,660 --> 00:01:55,210
We have a class for Agent.

26
00:01:55,210 --> 00:02:00,470
These are the people who list the different properties and we have in class for the user.

27
00:02:00,470 --> 00:02:03,230
These other people who browse between properties.

28
00:02:03,230 --> 00:02:06,410
Now all of these they share some attributes.

29
00:02:06,500 --> 00:02:12,870
Let's say they all have a status that is called active whether they are currently active or not.

30
00:02:12,880 --> 00:02:16,060
It is the property that is currently active or not an agent does.

31
00:02:16,070 --> 00:02:18,560
I will not use it as I will not.

32
00:02:18,560 --> 00:02:19,960
They will have a rating.

33
00:02:20,010 --> 00:02:25,160
So each of them at any given point has a rating user agent or property.

34
00:02:25,160 --> 00:02:28,310
Also they all have a function called rates.

35
00:02:28,320 --> 00:02:32,920
It's of course they all have a you idea they have a unique ID.

36
00:02:32,960 --> 00:02:34,420
So what they want to do is this.

37
00:02:34,450 --> 00:02:41,750
I want to make sure that this protocol includes all of these and every class that conforms to this protocol

38
00:02:41,750 --> 00:02:46,700
makes sure those classes have to incorporate these items in them.

39
00:02:46,820 --> 00:02:53,090
So the first thing is I'm going to say there is a valuable called active that is of the type Boolean

40
00:02:53,540 --> 00:02:57,220
and this is something that we can both get unset.

41
00:02:57,270 --> 00:03:03,230
This is essentially like that thing we had the read only or read the right and we'll get to see more

42
00:03:03,230 --> 00:03:09,320
of these things soon enough that there are items that we can or attributes that we can only read them

43
00:03:09,380 --> 00:03:12,700
or the ones that we can both read and write into them.

44
00:03:12,740 --> 00:03:17,910
So once we have that I have another value does of it is called you.

45
00:03:18,120 --> 00:03:19,920
ID is a string.

46
00:03:19,940 --> 00:03:24,860
And again it is a set and get we can both set and get them.

47
00:03:24,860 --> 00:03:31,480
We have something else called larger rate which is a float and this event is only.

48
00:03:31,480 --> 00:03:38,600
Yet we can not set it simply because rating should be calculated based on some some sort of algorithm

49
00:03:38,600 --> 00:03:44,570
something that calculates the value and tells us what the current weight rating is 4.2 or something

50
00:03:44,570 --> 00:03:45,650
to that effect.

51
00:03:45,710 --> 00:03:53,700
And then finally we have a function call rate it and this function doesn't have any body weight.

52
00:03:53,930 --> 00:04:01,550
Or maybe it has only one argument to rate it with import rate of a floater value and then like I said

53
00:04:01,610 --> 00:04:03,680
it doesn't have any logic.

54
00:04:03,680 --> 00:04:06,480
It just says this declaration exists.

55
00:04:06,530 --> 00:04:09,080
And that's the goal of having a protocol.

56
00:04:09,380 --> 00:04:13,100
Now let's go ahead and make our archery classes.

57
00:04:13,100 --> 00:04:14,540
I'm going to say I have a class.

58
00:04:14,540 --> 00:04:21,300
This course is going to be called property and it does conform to admissible.

59
00:04:21,500 --> 00:04:26,630
And the moment we do this we should see some sort of error given to us by the compiler OFX code.

60
00:04:26,630 --> 00:04:32,220
It's saying that it doesn't completely conform to this protocol you are missing some stuff.

61
00:04:32,240 --> 00:04:37,940
Would you like to add them I'm going to say yes and then it says well if you want to add them you have

62
00:04:37,940 --> 00:04:43,610
to make sure you have the activity you have the you ID you have the rating and you have this function

63
00:04:44,280 --> 00:04:47,870
and now that we have those we have to actually initialize this.

64
00:04:47,870 --> 00:04:52,920
We can just leave them there because the class is going to say well I know you have these three but

65
00:04:52,930 --> 00:04:55,310
when are you going are going to initialize them.

66
00:04:55,440 --> 00:05:01,390
I'm going to say in that and in the in it I'm going to say I haven't been active.

67
00:05:01,700 --> 00:05:02,820
That is half the time.

68
00:05:02,950 --> 00:05:09,590
And so when the initialise something is it active or not and then that to you idea and rate they have

69
00:05:09,590 --> 00:05:11,790
to be calculated at some other time.

70
00:05:11,810 --> 00:05:16,530
In that case active becomes Impe active.

71
00:05:16,940 --> 00:05:24,920
And then I'm going to say you ID for instance becomes you you ID dot you you idea string.

72
00:05:25,260 --> 00:05:29,550
And then the rate at the very very beginning we set it to be zero.

73
00:05:31,430 --> 00:05:40,930
And that whole my property class has conformed to the admissible protocol or Essentially it's been adapted

74
00:05:40,930 --> 00:05:44,480
to that and that's the same thing we have to do with everybody else.

75
00:05:44,500 --> 00:05:49,920
If we have a class called Agent we have to do that if you have a classical user you have to that.

76
00:05:50,020 --> 00:05:56,170
And of course each of these classes will have their own thing applying a protocol is very similar to

77
00:05:56,230 --> 00:06:01,160
writing three classes are making sure that each of the three classes have these.

78
00:06:01,360 --> 00:06:07,510
Even if it didn't have the protocol and we didn't have that this class would work on its own nothing

79
00:06:07,510 --> 00:06:13,410
is wrong with it having the political makes sure that we apply the same rule to everyone.

80
00:06:13,600 --> 00:06:16,020
I'm one of the places that we use protocols.

81
00:06:16,070 --> 00:06:19,430
Is isn't something that we call it delegation pattern.

82
00:06:19,630 --> 00:06:25,000
And that's something that you're going to see in an upcoming lesson which is a very very important part

83
00:06:25,000 --> 00:06:26,830
of you know Iowa's development.

84
00:06:27,010 --> 00:06:29,910
But for now Protocols are a set of rules.

85
00:06:29,920 --> 00:06:37,120
They have their instructions no logic they have the attributes and they know where they are get upset

86
00:06:37,150 --> 00:06:38,470
or only get.

87
00:06:38,620 --> 00:06:46,000
And then when we adopt them by any class it means all of those things in that protocol must exist in

88
00:06:46,000 --> 00:06:46,670
here.

89
00:06:47,140 --> 00:06:50,810
That function has to be there and those because they have to be there.

90
00:06:50,950 --> 00:06:52,740
And with that let's move on to our.