1
00:00:01,470 --> 00:00:04,020
We can now show a Google map on the screen which is great.

2
00:00:04,080 --> 00:00:09,150
But before we move on and start showing the markers there's one last little thing on a mentioned one

3
00:00:09,150 --> 00:00:11,660
to focus on the index dot t s file right now.

4
00:00:11,880 --> 00:00:13,490
I want to point out something inside of here.

5
00:00:13,530 --> 00:00:16,050
This is going to seem like a really strange thing to point out.

6
00:00:16,080 --> 00:00:18,340
Nonetheless I just want to mention it.

7
00:00:18,480 --> 00:00:22,530
Let's just take a look at a diagram I think you'll start to understand what I'm going to be talking

8
00:00:22,530 --> 00:00:22,980
about here.

9
00:00:23,630 --> 00:00:23,910
OK.

10
00:00:23,910 --> 00:00:25,400
So quick diagram.

11
00:00:25,500 --> 00:00:27,330
All right so this is kind of a crazy diagram.

12
00:00:27,330 --> 00:00:33,180
Its purpose is to try to show all the different things that we can effectively do inside the index dot

13
00:00:33,180 --> 00:00:37,970
t s file and I know that's weird to say but let's just kind of walk to the diagram step by step it's

14
00:00:37,970 --> 00:00:43,650
going to zoom in a little bit here and go up to the top so inside of our index dot t s file we've got

15
00:00:43,650 --> 00:00:46,800
an import statement for our company class.

16
00:00:46,830 --> 00:00:52,090
Now we currently have that commented out near we could very easily uncommon it with our company class.

17
00:00:52,140 --> 00:00:55,970
We have two things that we can effectively do with it.

18
00:00:56,070 --> 00:01:00,690
We can use it to create a new instance of a company and then with that instance of a company we can

19
00:01:00,690 --> 00:01:06,800
reference its company name catchphrase latitude longitude Likewise we've got the User class as well

20
00:01:07,950 --> 00:01:12,940
it's currently commented out but whatever we can easily uncommon commented with the User class we can

21
00:01:12,940 --> 00:01:18,210
create a new instance of it or and then reference that instances name latitude and longitude.

22
00:01:18,250 --> 00:01:23,590
So I'm just trying to describe like the total surface area of what we can do inside that index dot test

23
00:01:23,590 --> 00:01:24,700
file right now.

24
00:01:24,700 --> 00:01:29,650
And so that's basically what we can do with the company and the user there technically are other methods

25
00:01:29,650 --> 00:01:34,390
available to us like you know the name properties a string that has like a two upper case method and

26
00:01:34,390 --> 00:01:35,260
so on.

27
00:01:35,260 --> 00:01:39,970
I'm just trying to write out or diagram out all the different things that we've added into our application

28
00:01:39,970 --> 00:01:46,350
that's specific to our application so in other words the surface area of the company and the user classes

29
00:01:46,410 --> 00:01:48,540
is quite small.

30
00:01:48,540 --> 00:01:52,530
Let's now start to think about that map we just created however I need to zoom back out just a little

31
00:01:52,530 --> 00:01:53,550
bit.

32
00:01:53,680 --> 00:01:56,590
So in the last video we created that Google map right.

33
00:01:56,620 --> 00:02:01,290
So we said right here we said new Google Maps map dot map.

34
00:02:01,290 --> 00:02:07,020
This creates an instance of a map right here we could technically assign the results of that to a variable

35
00:02:08,370 --> 00:02:14,990
like so and then down here we could write out map and try to call a bunch of different methods attached

36
00:02:14,990 --> 00:02:16,160
to that Google map we created.

37
00:02:16,160 --> 00:02:20,750
So if I put a dot right there I'll see all the different methods that are attached to a map.

38
00:02:20,820 --> 00:02:25,880
So I see add listener bind to changed fit bounds get get bounce all these different things.

39
00:02:25,880 --> 00:02:29,390
Those are all different methods we actually saw inside the type definition file.

40
00:02:29,390 --> 00:02:33,620
So another way of seeing all those different methods would once again be to command click on map right

41
00:02:33,620 --> 00:02:36,740
there and you'll see all those same functions listed out right here.

42
00:02:36,740 --> 00:02:40,890
These are all functions that belong to that instance of a map.

43
00:02:40,970 --> 00:02:44,270
And so those are what these boxes all represent size diagram right here.

44
00:02:44,270 --> 00:02:49,220
So we've got methods like set zoom set center set street view and so on.

45
00:02:49,220 --> 00:02:51,050
So why is this relevant.

46
00:02:51,050 --> 00:02:55,170
Well there's going to seem like a weird thing by just want to point it out.

47
00:02:55,310 --> 00:03:00,470
These are all methods that we have exposed inside of our index dot t yes file.

48
00:03:00,470 --> 00:03:06,080
So if another engineer started to come into our project they could look at that map variable and say

49
00:03:06,350 --> 00:03:12,170
oh hey look at these cool methods attach the map you know what I feel like just starting to call them.

50
00:03:12,200 --> 00:03:17,810
So another engineer might come into our project start calling the methods associated with that map in

51
00:03:17,810 --> 00:03:20,640
very easily break our application.

52
00:03:21,170 --> 00:03:22,890
I know that sounds strange.

53
00:03:22,910 --> 00:03:26,060
I know that's weird like that's the job of Google Maps right.

54
00:03:26,060 --> 00:03:29,600
Google Maps is here to expose all these different methods.

55
00:03:29,600 --> 00:03:35,830
My only point is that you and I as the sole developers of this application have not vetted these methods

56
00:03:35,840 --> 00:03:40,610
we haven't sat down and said Oh yeah if you call these things our application is going to continue to

57
00:03:40,610 --> 00:03:42,050
work perfectly.

58
00:03:42,050 --> 00:03:43,380
We didn't do that.

59
00:03:43,400 --> 00:03:50,800
So in theory if someone started to call these methods it might horribly break our application again.

60
00:03:50,810 --> 00:03:58,520
I know this sounds like a stretch but let me just make a suggestion maybe if we found out a way to limit

61
00:03:58,610 --> 00:04:04,790
other engineers access to these methods right here maybe that would just slightly decrease the chances

62
00:04:05,090 --> 00:04:07,530
of our application breaking horribly.

63
00:04:07,610 --> 00:04:14,390
So here's what I'm going to suggest maybe we start to like firm up or limit the number of things we

64
00:04:14,390 --> 00:04:16,420
can do inside the index not TSA file.

65
00:04:16,460 --> 00:04:23,360
Maybe we say the only things you can do inside of this file is create a new company reference its properties.

66
00:04:23,360 --> 00:04:30,200
Create a new user reference its properties and then maybe we should create a new class called Map like

67
00:04:30,200 --> 00:04:37,060
our own custom map class and this custom map class can be used to create a new instance of a Google

68
00:04:37,060 --> 00:04:37,870
map.

69
00:04:37,930 --> 00:04:42,730
So this right here like will create a new instance of map to be precise and during that process we can

70
00:04:42,730 --> 00:04:48,640
create a new instance of a Google map and also on that map class we can add a method called Ad marker

71
00:04:49,210 --> 00:04:54,460
and we'll use that function right there to achieve our original goal this application of showing a marker

72
00:04:54,460 --> 00:04:56,410
for user and company on the actual map.

73
00:04:57,490 --> 00:05:01,250
So again this class right here you and I are going to create this is like maybe a better name for a

74
00:05:01,250 --> 00:05:08,630
be like custom map like so so then wrapped up inside this class we will have some logic to create a

75
00:05:08,630 --> 00:05:15,160
Google map and the important thing here is that that Google map and all of its associated dangerous

76
00:05:15,160 --> 00:05:22,030
functions and methods right here will not be easily exposed inside of our index dot t s file and so

77
00:05:22,030 --> 00:05:27,130
if another engineer came into our project they can't just open up that index dot test file and start

78
00:05:27,130 --> 00:05:30,120
calling random methods on the Google map.

79
00:05:30,430 --> 00:05:35,590
Instead we've hidden all those methods we've wrapped them all up and taken them away from engineers

80
00:05:35,800 --> 00:05:42,200
and hidden them behind this facade of sorts or this kind of like black box of custom map.

81
00:05:42,460 --> 00:05:47,990
And the only thing you can do with custom map is create a new map and add a marker to it again.

82
00:05:47,990 --> 00:05:52,670
I know this sounds like a stretch but the whole idea here is that if we have a program where these are

83
00:05:52,670 --> 00:05:55,370
like the only things you can do.

84
00:05:55,550 --> 00:06:00,050
Chances are it's going to be way more challenging for people to come into our app and start to break

85
00:06:00,050 --> 00:06:01,480
things.

86
00:06:01,550 --> 00:06:03,210
All right so let's take a quick pause right here.

87
00:06:03,260 --> 00:06:09,290
When we come back the next video we're going to start to extract this logic to create a Google map right

88
00:06:09,290 --> 00:06:11,940
here into a new class.

89
00:06:12,050 --> 00:06:17,270
And once again this logic to create a Google map is going to wrap up all that stuff or Sammy our new

90
00:06:17,270 --> 00:06:22,340
class is going to wrap up the Google map and try to hide its existence from other engineers so they

91
00:06:22,340 --> 00:06:25,470
can't accidentally break our application.

92
00:06:25,500 --> 00:06:25,710
All right.

93
00:06:25,710 --> 00:06:26,770
So quick pause right here.

94
00:06:26,820 --> 00:06:28,070
Take care of that in the next video.