1 00:00:00,450 --> 00:00:07,140 If you got stuck or if you had any problems completing this project, the first port of call is to review 2 00:00:07,140 --> 00:00:08,380 the lessons you learned today. 3 00:00:08,760 --> 00:00:14,280 It might just be that you need to see some of the theory a few more times and listen to it a few more 4 00:00:14,280 --> 00:00:19,410 times and practice it a few more times before you're ready to tackle this final challenge. 5 00:00:20,070 --> 00:00:24,660 But if you have completed it and you just want to see the solution, then I'm going to go through it 6 00:00:24,660 --> 00:00:25,380 with you right now. 7 00:00:26,400 --> 00:00:30,210 Again, we're going to complete all of the program requirements step by step. 8 00:00:30,570 --> 00:00:38,610 So the first thing is to print a report for all of the current resources in the coffee machine. Back 9 00:00:38,610 --> 00:00:39,090 in PyCharm, 10 00:00:39,330 --> 00:00:44,310 I'm actually going to collapse this entire project folder because I'm not going to be writing any code 11 00:00:44,310 --> 00:00:46,140 other than inside main.py. 12 00:00:47,040 --> 00:00:54,270 Now you can see up here, we've got access to four classes. And if we take a look inside the documentation, 13 00:00:54,480 --> 00:01:00,990 you can see that both the coffeemaker class and the money machine class have a method called report. 14 00:01:01,560 --> 00:01:06,690 And this is going to print a report of all of the resources like water, milk, coffee, 15 00:01:06,990 --> 00:01:09,810 and this is going to print a report of the current profit. 16 00:01:10,260 --> 00:01:16,290 So our final report is going to be both a report from the money machine as well as the coffee maker. 17 00:01:17,310 --> 00:01:22,380 Let's go ahead and start off by creating some objects from these classes. 18 00:01:22,950 --> 00:01:27,840 For example, the money machine is going to be just called money_machine 19 00:01:27,870 --> 00:01:30,250 or you could call it my_money_machine. 20 00:01:30,270 --> 00:01:33,090 You can actually name your objects anything you like. 21 00:01:33,720 --> 00:01:41,160 But I'm just going to use the default Python snake case to create a new variable money_machine, which 22 00:01:41,160 --> 00:01:46,980 is going to hold my object. And my object is going to be created, of course, from the money machine 23 00:01:46,980 --> 00:01:47,520 class. 24 00:01:48,090 --> 00:01:51,900 And the construction happens when I add the parentheses. 25 00:01:52,500 --> 00:01:58,440 So now I have a object created and stored inside this variable money_machine. 26 00:01:59,280 --> 00:02:06,870 Now, if I want this money machine to create a report, then all I have to do is tap into the object 27 00:02:07,260 --> 00:02:12,360 and then write a dot and then call the method that I need, which is report. 28 00:02:13,020 --> 00:02:15,630 So now if I go ahead and run my code, 29 00:02:18,360 --> 00:02:22,110 you can see it prints out the current amount of money in the machine. 30 00:02:22,890 --> 00:02:25,710 Now let's do the same thing for our coffee maker. 31 00:02:26,630 --> 00:02:31,010 Again, I'm going to call it coffee_maker, and you see this frequently. 32 00:02:31,020 --> 00:02:39,840 The object naming tends to be the lower case and snake case, so separated by underscores, version of the 33 00:02:39,840 --> 00:02:40,740 name of the class. 34 00:02:40,950 --> 00:02:47,580 So the name of the class is CoffeeMaker, and usually you'll see people name the object exactly the 35 00:02:47,580 --> 00:02:49,290 same, but in lowercase. 36 00:02:50,280 --> 00:02:57,900 And now that I have my coffee _maker, then I can go ahead and call the report method on that object 37 00:02:57,900 --> 00:02:58,410 as well. 38 00:02:58,800 --> 00:03:04,980 And now, if I run my code once more, you can see that I've got everything now being reported and printed 39 00:03:04,980 --> 00:03:05,190 out. 40 00:03:06,060 --> 00:03:12,870 So in this case, we don't actually have to care how report is implementing all of this functionality. 41 00:03:13,200 --> 00:03:19,470 All we have to do is read the documentation, find the method that does the thing that we want, and 42 00:03:19,470 --> 00:03:23,640 then trust that it will carry out the functionality as described. 43 00:03:24,870 --> 00:03:30,480 Now that we've completed step 1, the next one is to check that resources are sufficient. 44 00:03:31,080 --> 00:03:35,370 My first port of call is going to be going over to the documentation. 45 00:03:35,820 --> 00:03:42,240 And you can see that the coffeemaker class actually has a method called is _resource_efficient. 46 00:03:42,600 --> 00:03:50,130 And all we have to do is pass in the drink, which is a menu item, and then it's going to check and 47 00:03:50,130 --> 00:03:56,640 give us true, if that drink order can be made, and false if the ingredients are insufficient. 48 00:03:57,840 --> 00:04:03,930 So how do we get hold of this drink menu item to pass over to this method? 49 00:04:04,650 --> 00:04:11,700 Well, if we take a look at the menu class, you can see it has a method called get_items and this is 50 00:04:11,700 --> 00:04:15,030 where you really see reading the documentation properly, 51 00:04:15,450 --> 00:04:19,800 actually absorbing everything that's in here becomes really, really helpful. 52 00:04:20,459 --> 00:04:24,570 This menu class has two methods that are really useful. 53 00:04:25,050 --> 00:04:30,870 One, It's able to get a hold of the names of all the items that are available on the menu. 54 00:04:31,350 --> 00:04:35,370 And it returns it as a string separated by forward slashes. 55 00:04:36,120 --> 00:04:40,560 It's also able to find a drink based on the order name. 56 00:04:40,590 --> 00:04:47,550 So if we passed in one of these names to this function find_drink, then it's going to return a menu 57 00:04:47,550 --> 00:04:49,770 item object if it actually exists. 58 00:04:50,040 --> 00:04:51,990 Otherwise, it's going to return none. 59 00:04:52,620 --> 00:04:56,670 We're going to need both of these in order to ask the user what they want. 60 00:04:57,530 --> 00:05:02,520 Let's go ahead and set up our while loop. As we had previously 61 00:05:02,540 --> 00:05:08,660 I'm going to create a new variable called is_on and it's going to start off being true. 62 00:05:09,230 --> 00:05:16,880 And then while coffee machine is on, well then we're going to get hold of all the options that we 63 00:05:16,880 --> 00:05:22,850 can offer the user. And we get that by calling that method get_items. 64 00:05:23,300 --> 00:05:28,580 But of course, because this is a method, it's associated with an object. 65 00:05:28,670 --> 00:05:32,240 So we have to create an object from this menu blueprint. 66 00:05:33,440 --> 00:05:36,770 So let's do that next to all the other objects being created. 67 00:05:37,190 --> 00:05:42,050 So let's create a menu object and it's going to be created from the menu class, 68 00:05:42,050 --> 00:05:43,640 and then we add the parentheses. 69 00:05:44,030 --> 00:05:47,840 And now we have access to that object by the name menu. 70 00:05:48,380 --> 00:05:54,800 The options are going to be equal to the menu object and then we're going to call the get_items method. 71 00:05:55,340 --> 00:06:01,580 And then when this method returns, it's going to save the string and all the options into this variable 72 00:06:01,580 --> 00:06:02,390 called options. 73 00:06:02,990 --> 00:06:09,800 Now we can get the user's choice by asking them for what would you like? 74 00:06:11,170 --> 00:06:17,650 And then inside a set of parenthesis we'll offer them all the options. And then, of course, I need 75 00:06:17,650 --> 00:06:19,480 to turn this into an fstring. 76 00:06:19,630 --> 00:06:24,070 And the code highlighting immediately tells me that this is actually now working. 77 00:06:24,640 --> 00:06:32,740 So once I've got the user's choice, then I can incorporate the reporting behaviour into this choice. 78 00:06:33,130 --> 00:06:42,310 Remember, previously we said if the choice was equal to off, then that means the is_on is going 79 00:06:42,310 --> 00:06:45,390 to be equal to false, and elif 80 00:06:45,400 --> 00:06:47,860 the choice is equal to report, 81 00:06:48,310 --> 00:06:53,110 well, in this case, we're going to get the coffeemaker and the money machine to make their reports 82 00:06:53,110 --> 00:06:54,040 into the console. 83 00:06:54,970 --> 00:07:03,040 Finally, we're ready to tackle the next problem, which is how do we check that we have enough resources? 84 00:07:04,100 --> 00:07:10,520 And this is going to require us to find the drink given the order name that the user chose from the 85 00:07:10,520 --> 00:07:17,440 choice and then get hold of the menu item which comes as the output from this method call. 86 00:07:18,430 --> 00:07:26,110 So else, we're going to save our drink as a variable called drink, and then we're going to tap into 87 00:07:26,110 --> 00:07:35,500 the menu.find_drink. And find_drink, you'll notice, takes a order name as the input. 88 00:07:35,980 --> 00:07:42,370 So this is a string and this is going to be equal to whatever the user chose inside this choice. 89 00:07:42,940 --> 00:07:45,910 So let's put the choice in here as the input. 90 00:07:46,450 --> 00:07:51,190 And now, once we've got hold of this drink, let's go ahead and print it. 91 00:07:51,820 --> 00:07:55,930 Remember, we're expecting a menu item object at this stage. 92 00:07:56,500 --> 00:08:01,480 So let's click run, and let's make sure that we can hit report to get the report, 93 00:08:01,870 --> 00:08:11,440 we can say off to switch off the machine and exit the code, and we can also get hold of a latte by 94 00:08:11,440 --> 00:08:14,530 passing in latte as the drink that we want. 95 00:08:15,040 --> 00:08:21,940 And we now get printed a menu item object at this particular location in the computer's memory. 96 00:08:22,450 --> 00:08:23,040 Perfect. 97 00:08:23,050 --> 00:08:25,330 Everything is working as expected. 98 00:08:26,140 --> 00:08:32,590 Now, instead of printing the drink, I'm going to tackle this step 2, which is to check that the 99 00:08:32,590 --> 00:08:34,330 resources are sufficient. 100 00:08:35,440 --> 00:08:42,400 Again, that's going to require us to look through our documentation. And you'll see that the coffee 101 00:08:42,400 --> 00:08:43,600 maker class has 102 00:08:43,600 --> 00:08:50,260 that method is_resource _sufficient, and it expects a menu item object as the input. 103 00:08:50,710 --> 00:08:54,970 And then it's going to return true when it can be made and false if it can't. 104 00:08:55,960 --> 00:09:03,550 So let's get hold of our coffee maker object and then get it to check if the resources are sufficient 105 00:09:03,940 --> 00:09:07,000 to make the current drink that we're interested in. 106 00:09:07,870 --> 00:09:11,770 And let's go ahead and print the results here 107 00:09:12,820 --> 00:09:14,350 and run our code. 108 00:09:15,190 --> 00:09:23,290 Let's say that we wanted to make a latte. That's going to be resource sufficient, so true. Espresso, 109 00:09:23,620 --> 00:09:27,560 also true, and a Cappuccino is also true. 110 00:09:27,580 --> 00:09:29,740 So we can make all three drinks, basically. 111 00:09:30,070 --> 00:09:37,480 Now, instead of printing this, what we want to do is we want to check if this is true and then proceed 112 00:09:37,480 --> 00:09:40,210 to the next step if there are enough resources. 113 00:09:40,870 --> 00:09:47,830 Now the next step is to take payment from the user and to process the coins and check the transaction 114 00:09:47,830 --> 00:09:48,700 is successful. 115 00:09:49,630 --> 00:09:56,980 Notice how in our coffee machine documentation for the money machine, we don't actually have a way 116 00:09:56,980 --> 00:10:05,050 of processing the coins. But it what it does have is it allows us to make payments passing in the cost 117 00:10:05,050 --> 00:10:11,530 of the drink and then it will return true when the payment is accepted or false, if insufficient. 118 00:10:12,160 --> 00:10:15,650 So let's see what happens if we actually try to make payment. 119 00:10:16,510 --> 00:10:23,110 Let's tap into our money machine object and then call the make_payment method and we have to pass in 120 00:10:23,110 --> 00:10:26,170 the cost of the drink that the user ordered. 121 00:10:26,710 --> 00:10:34,480 So we've got the drink object here, which remember is a menu item, and each of the menu items have 122 00:10:34,480 --> 00:10:39,880 three attributes that we care about: the name of the drink, the cost of the drink and the ingredient 123 00:10:39,880 --> 00:10:40,240 list. 124 00:10:40,630 --> 00:10:49,360 So this is what we're interested in at the moment. So we can pass in the drink.cost which is the 125 00:10:49,360 --> 00:10:52,270 attribute that's associated with the drink object, 126 00:10:52,750 --> 00:10:59,110 and that cost is going to be processed by this make_payment method from the money machine. 127 00:10:59,740 --> 00:11:05,020 And then finally, it's going to tell us whether if this was successful or not. 128 00:11:05,410 --> 00:11:08,200 So let's see what happens when we run this code as it is. 129 00:11:09,230 --> 00:11:11,230 Let's say I wanted a latte, 130 00:11:12,170 --> 00:11:14,820 notice how it's asking me to insert coins: 131 00:11:14,840 --> 00:11:22,340 how many quarters, how many dimes, how many nickels and how many pennies. A the coffee machine, 132 00:11:22,700 --> 00:11:28,490 I don't actually need to care about how the money and the coins are processed. 133 00:11:29,090 --> 00:11:35,180 All I had to do is call make_payment and it deals with all of this automatically. 134 00:11:36,170 --> 00:11:43,430 Finally, it gives me the change and it returns true, telling me that this make_payment was indeed 135 00:11:43,430 --> 00:11:44,240 successful. 136 00:11:45,140 --> 00:11:52,610 If you actually look inside the money_machine code, then you can see that it has a method called process_ 137 00:11:52,610 --> 00:11:56,790 coins, but it's called when make payment is triggered. 138 00:11:57,290 --> 00:12:02,960 This class is going to process coins, and then it's going to decide whether if it was successful 139 00:12:03,170 --> 00:12:07,820 or not. And if it was successful, it's going to add the cost to the profit, 140 00:12:08,120 --> 00:12:13,130 and if not, it's going to tell you that that was not enough money and your money is refunded. 141 00:12:14,980 --> 00:12:23,620 Coming back over here, if this is successful, then that means the user has managed to pay and we fulfilled 142 00:12:23,680 --> 00:12:27,850 step 3 and 4 just using one method. 143 00:12:28,960 --> 00:12:32,440 The final thing we have to do is to actually make the coffee. 144 00:12:33,160 --> 00:12:35,830 And that, of course, happens right at the end here. 145 00:12:36,430 --> 00:12:42,730 And all we have to do to make the coffee is get hold of the coffee maker object and then call the make_ 146 00:12:42,730 --> 00:12:48,220 coffee method and we can pass in the order, which is our drink. 147 00:12:48,700 --> 00:12:54,850 Because remember that the make_coffee method expects a menu item as the input parameter. 148 00:12:55,990 --> 00:13:03,280 We can actually simplify this code even more by saying, well, if the coffee maker is_resource_sufficient 149 00:13:04,030 --> 00:13:11,620 and the money machine was able to take payment, well then we can get the coffee_maker to make coffee. 150 00:13:12,310 --> 00:13:14,320 So now let's go ahead and run our code. 151 00:13:16,530 --> 00:13:21,930 And let's report to begin with, to see how much resources we have to begin with. 152 00:13:22,380 --> 00:13:24,780 And then let's order a coffee. 153 00:13:26,930 --> 00:13:30,890 Insert lots of money and we've got our coffee back. 154 00:13:31,400 --> 00:13:39,800 So now let's go ahead and order a different coffee, latte, and let's go ahead and insert lots of money. 155 00:13:40,370 --> 00:13:42,380 And you can see, here's my latte. 156 00:13:42,770 --> 00:13:49,910 But now, if I hit report, you can see that the objects, the coffee maker has been managing our resources 157 00:13:50,420 --> 00:13:53,240 and the money_machine has been managing our profit. 158 00:13:53,960 --> 00:13:59,900 Now, if I decided to order another latte, then it should actually tell me, sorry, there's not enough 159 00:13:59,900 --> 00:14:04,520 water and there's not enough milk. So it can't make me that drink. 160 00:14:05,150 --> 00:14:12,650 And we've managed to achieve all of this functionality by writing very few lines of code, and the code 161 00:14:12,650 --> 00:14:16,130 itself is actually very, very easy to understand. 162 00:14:16,370 --> 00:14:22,840 Even if you came to this completely fresh, you've never seen how each of the methods are implemented, 163 00:14:22,850 --> 00:14:24,440 you don't know how the coffee maker works, 164 00:14:24,710 --> 00:14:26,240 you don't know how the money machine works, 165 00:14:26,540 --> 00:14:29,000 you can see quite easily what it's trying to do. 166 00:14:29,960 --> 00:14:35,660 And so if you only have to write this kind of code, then it would make it so much easier to create 167 00:14:35,660 --> 00:14:39,440 even more complex functionality in your coffee machine, right? 168 00:14:40,430 --> 00:14:43,130 So have a play around with these classes: 169 00:14:43,580 --> 00:14:50,270 the coffeeMaker, the moneyMachine, the menu, the menu item, etc. And see what else it is that 170 00:14:50,270 --> 00:14:51,590 you can do with this code 171 00:14:51,860 --> 00:14:55,880 while not touching any of the blueprints for each of these classes. 172 00:14:57,200 --> 00:15:02,660 Now, in the next lesson, I'm going to be showing you how to create your own classes so that you can 173 00:15:02,660 --> 00:15:07,880 actually start structuring your code using full object-oriented programming. 174 00:15:08,390 --> 00:15:14,420 And we're going to learn about these things like the initialization and how classes are declared and 175 00:15:14,420 --> 00:15:16,910 why there's all this self all over the place. 176 00:15:17,630 --> 00:15:20,480 That's all yet to come on tomorrow's lessons.