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+1
+00:00:00,260 --> 00:00:01,720
+Okay, so let me see if
+
+2
+00:00:01,720 --> 00:00:07,930
+anything changed after we did this last modification.
+
+3
+00:00:07,930 --> 00:00:09,530
+Acutally, there is someting that I would like
+
+4
+00:00:09,530 --> 00:00:12,120
+to do here. Because looking at this a little
+
+5
+00:00:12,120 --> 00:00:15,560
+bit more, I noticed that there are two
+
+6
+00:00:15,560 --> 00:00:18,760
+attributes, renewed and due date. That we have in
+
+7
+00:00:18,760 --> 00:00:21,640
+loanable Item, right? But they don't seem to
+
+8
+00:00:21,640 --> 00:00:25,590
+be really, attributes or characteristics of loanable Item.
+
+9
+00:00:25,590 --> 00:00:29,150
+They're more of the characteristics of the association between the
+
+10
+00:00:29,150 --> 00:00:31,450
+Loanable Item and the patron. Wouldn't you agree?
+
+11
+00:00:32,470 --> 00:00:34,230
+>> Well, yeah, it's not like you could
+
+12
+00:00:34,230 --> 00:00:37,644
+only renew a book once in it's entire history.
+
+13
+00:00:37,644 --> 00:00:41,220
+>> Right. Exactly, exactly. So, that's why what l like
+
+14
+00:00:41,220 --> 00:00:43,970
+to do is I would like to move those out of loanable
+
+15
+00:00:43,970 --> 00:00:48,020
+item. And actually there is a construct that we can use
+
+16
+00:00:48,020 --> 00:00:50,710
+to express this. It's called, we haven't seen it yet, but it's
+
+17
+00:00:50,710 --> 00:00:52,780
+a special kind of class. It's called an association
+
+18
+00:00:52,780 --> 00:00:55,480
+class. So, it's a class that is connected to
+
+19
+00:00:55,480 --> 00:00:57,730
+a specific association. So what we can do
+
+20
+00:00:57,730 --> 00:01:00,730
+here, we can create this class, which I'm going to
+
+21
+00:01:00,730 --> 00:01:05,200
+call checked out. I'm going to, associate it with
+
+22
+00:01:05,200 --> 00:01:09,520
+this, association. I'm going to connect it with this association. And
+
+23
+00:01:09,520 --> 00:01:11,620
+then I'm going to move the due date and the
+
+24
+00:01:11,620 --> 00:01:16,300
+renewed attributes From the LoanableItem here in this checked
+
+25
+00:01:16,300 --> 00:01:18,520
+out class. So in this way, seems to me that
+
+26
+00:01:18,520 --> 00:01:20,910
+it makes it very explicit for somebody looking at this
+
+27
+00:01:20,910 --> 00:01:25,530
+class diagram, that these characteristics are characteristics of the loan,
+
+28
+00:01:25,530 --> 00:01:28,200
+and not of the elements involved in the loan.
+
+29
+00:01:28,200 --> 00:01:33,410
+>> Can you do the same thing with Fine, isn't Fine a property of the
+
+30
+00:01:33,410 --> 00:01:36,740
+loan? Yeah, actually is right because
+
+31
+00:01:36,740 --> 00:01:39,120
+a fine is a fine for a specific loan, right?
+
+32
+00:01:39,120 --> 00:01:39,910
+>> That's correct.
+
+33
+00:01:39,910 --> 00:01:41,950
+>> Okay, so yeah. Then we can do that.
+
+34
+00:01:41,950 --> 00:01:45,900
+We don't need to represent fine as a class, we can just transform
+
+35
+00:01:45,900 --> 00:01:49,460
+that into an attribute that we can put into the checked out association class.
+
+36
+00:01:49,460 --> 00:01:50,560
+>> Gotcha.
+
+37
+00:01:50,560 --> 00:01:52,760
+>> Anything else?
+
+38
+00:01:52,760 --> 00:01:57,990
+>> Yeah. It occurred to me that there's another thing that happens in one
+
+39
+00:01:57,990 --> 00:02:00,260
+of my scenarios, I put down
+
+40
+00:02:00,260 --> 00:02:02,770
+about the patron actually returning an item.
+
+41
+00:02:02,770 --> 00:02:07,620
+>> Right. Okay, so we would probably need an additional operation,
+
+42
+00:02:07,620 --> 00:02:08,550
+I guess, for the patron.
+
+43
+00:02:08,550 --> 00:02:08,990
+>> Right.
+
+44
+00:02:08,990 --> 00:02:11,310
+>> So, okay, so what I'm going to do, that's pretty easy
+
+45
+00:02:11,310 --> 00:02:15,350
+to do, I'm just going to add the return operation here in the
+
+46
+00:02:15,350 --> 00:02:19,310
+patron, and when that happens, that will mean that I'll get rid
+
+47
+00:02:19,310 --> 00:02:23,490
+of this association class because the item is returned. Is that right?
+
+48
+00:02:23,490 --> 00:02:27,060
+>> Well, what happens if somebody drops the
+
+49
+00:02:27,060 --> 00:02:29,400
+book in the book drop, but doesn't pay the,
+
+50
+00:02:29,400 --> 00:02:31,050
+if it's overdue and doesn't pay the fine?
+
+51
+00:02:31,050 --> 00:02:32,700
+Will that get rid of the information about what
+
+52
+00:02:32,700 --> 00:02:33,040
+they owe?
+
+53
+00:02:33,040 --> 00:02:37,960
+>> Oh, I see. So you can have the item being available, but you still
+
+54
+00:02:37,960 --> 00:02:42,510
+want to know whether there is any pending fines on the book.
+
+55
+00:02:42,510 --> 00:02:44,390
+>> Uh-huh, and how much those fines are.
+
+56
+00:02:44,390 --> 00:02:46,340
+>> And how do you compute how much it is?
+
+57
+00:02:47,420 --> 00:02:52,710
+>> It's how many days it was, from the time it was
+
+58
+00:02:52,710 --> 00:02:58,170
+due, to when they returned it. I see. OK.
+
+59
+00:02:58,170 --> 00:03:00,380
+So you know what we can do? I think
+
+60
+00:03:00,380 --> 00:03:03,690
+we can put an additional attribute in the checked out
+
+61
+00:03:03,690 --> 00:03:07,190
+class and I'm going to call it when returned and
+
+62
+00:03:07,190 --> 00:03:10,200
+that item will have either a special value or it
+
+63
+00:03:10,200 --> 00:03:12,040
+will contain the date in which the book was
+
+64
+00:03:12,040 --> 00:03:14,520
+returned. So in this way you should be able to
+
+65
+00:03:14,520 --> 00:03:18,040
+keep this in the system until it's paid, and also to compute
+
+66
+00:03:18,040 --> 00:03:19,970
+how much the fine is. Is that working?
+
+67
+00:03:19,970 --> 00:03:23,210
+>> So the special value is for a normal situation when they
+
+68
+00:03:23,210 --> 00:03:25,880
+haven't, they don't owe anything and haven't returned it yet.
+
+69
+00:03:25,880 --> 00:03:28,080
+>> Exactly so that will tell us that,
+
+70
+00:03:28,080 --> 00:03:29,970
+that the loan is still active basically.
+
+71
+00:03:29,970 --> 00:03:30,500
+>> Great.
+
+72
+00:03:30,500 --> 00:03:31,480
+>> Does that work for you?
+
+73
+00:03:31,480 --> 00:03:35,200
+>> Yes. And you know, I like this. I mean, I feel pretty good
+
+74
+00:03:35,200 --> 00:03:38,490
+about it. I think we have a nice class diagram. So what I'd like to
+
+75
+00:03:38,490 --> 00:03:43,280
+do is just go off and clean it up a little bit, and put it
+
+76
+00:03:43,280 --> 00:03:48,640
+in an IDE so I can pretty print it and rearrange things a little bit.
+
+77
+00:03:48,640 --> 00:03:50,080
+And then I'd like to sit down again and
+
+78
+00:03:50,080 --> 00:03:52,730
+just go through it for a last time. And
+
+79
+00:03:52,730 --> 00:03:54,900
+for some final considerations. So if you don't mind
+
+80
+00:03:54,900 --> 00:03:56,880
+we will take a ten minute break and reconvene here.
+
+81
+00:03:56,880 --> 00:03:57,500
+>> That's fine.
+
+82
+00:03:57,500 --> 00:03:57,990
+>> Alright.
+