1 00:00:00,700 --> 00:00:03,490 Hi, and welcome to today's bonus example. 2 00:00:03,490 --> 00:00:09,760 In yesterday's bonus example, we worked on this code, so if you haven't seen that video yet, please 3 00:00:09,760 --> 00:00:12,760 do so because that video is related to this one. 4 00:00:12,760 --> 00:00:18,220 In a nutshell, what we did is we asked the user to enter Ft and inches, so we got that as a string 5 00:00:18,220 --> 00:00:18,460 here. 6 00:00:18,460 --> 00:00:22,570 And then this convert function extracted the numbers from that string. 7 00:00:23,290 --> 00:00:30,280 So if the user entered 312, for example, we extracted three and 12 and we convert them into floats 8 00:00:30,280 --> 00:00:35,320 here and there and we calculated meters out of those two numbers. 9 00:00:35,320 --> 00:00:40,630 So three and 12, we multiply that by that number and that's by that and we got meters. 10 00:00:40,630 --> 00:00:48,730 So this was good to return a number instead of a string where you had meters inside the string and you 11 00:00:48,730 --> 00:00:51,400 had some other information here text. 12 00:00:51,610 --> 00:00:59,890 So that was not good because we couldn't use that output in other parts of the codes as we do here. 13 00:00:59,890 --> 00:01:01,210 So here we want to. 14 00:01:01,890 --> 00:01:05,489 Compare that meters with some other value. 15 00:01:05,610 --> 00:01:08,460 So it's good to decouple your output. 16 00:01:08,490 --> 00:01:18,330 The problem this brought about was that now what if we want to print out the feed value that the user 17 00:01:18,330 --> 00:01:20,160 entered so feeds? 18 00:01:20,160 --> 00:01:26,070 We cannot access that value from that function because that feed is a local variable. 19 00:01:26,070 --> 00:01:37,920 So we cannot say that and same four inches is equal to we can get meters because meters is the output. 20 00:01:37,920 --> 00:01:44,340 So when we return a variable, a local variable, that variable can be accessed through the function 21 00:01:44,340 --> 00:01:45,000 call. 22 00:01:45,000 --> 00:01:46,350 So that's okay. 23 00:01:46,350 --> 00:01:46,980 We can. 24 00:01:47,890 --> 00:01:49,030 Access results. 25 00:01:49,030 --> 00:01:50,890 But how do we access FT and inches? 26 00:01:50,920 --> 00:01:55,360 Well, the problem lies again in decoupling. 27 00:01:55,390 --> 00:01:58,390 Today, we're going to talk about decoupling functions. 28 00:01:58,420 --> 00:02:00,580 Yesterday, we talked about decoupling output. 29 00:02:00,610 --> 00:02:03,070 Now, this function is doing too much. 30 00:02:03,100 --> 00:02:04,360 It's doing two things. 31 00:02:04,360 --> 00:02:07,750 First, it is passing that string. 32 00:02:07,750 --> 00:02:12,640 So the user enters FT and inches and the function is splitting it. 33 00:02:12,640 --> 00:02:20,520 And then it's extracting numbers from that string and then it converts those to numbers into meters. 34 00:02:20,530 --> 00:02:23,490 However, the name of the function is convert. 35 00:02:23,500 --> 00:02:29,160 So this function is doing too much functions should do one thing and do it well. 36 00:02:29,170 --> 00:02:31,390 So the solution here is decoupling. 37 00:02:31,390 --> 00:02:35,410 And the way we do decoupling here is by creating two different functions. 38 00:02:36,310 --> 00:02:41,320 Let's call this pass or extract whatever we like. 39 00:02:41,470 --> 00:02:51,460 So pause and feed inches goes as the inputs of this pause function, and then this code goes in here. 40 00:02:51,760 --> 00:02:59,620 So we get ports, we say feed inches, split feed is converted into floats, interest is converted into 41 00:02:59,620 --> 00:03:00,700 float as well. 42 00:03:00,700 --> 00:03:03,370 And then we return those two numbers. 43 00:03:03,370 --> 00:03:10,840 So we make these two numbers basically available to be accessed from the other components of the script. 44 00:03:10,840 --> 00:03:13,510 You can see fit and inches. 45 00:03:13,510 --> 00:03:17,080 So if I demonstrate you what I'm doing here, this should work. 46 00:03:17,080 --> 00:03:21,400 Like this lets me paste this function here in the python console. 47 00:03:21,400 --> 00:03:30,520 So pause if we call it and we say 412 and we press enter, what we get in return is a tuple with these 48 00:03:30,520 --> 00:03:31,240 two values. 49 00:03:31,240 --> 00:03:38,440 So when you return to variables, they're what you get in return is not one value, but two values enclosed 50 00:03:38,440 --> 00:03:39,310 in a tuple. 51 00:03:39,310 --> 00:03:48,190 So if you check the type of that value, it's going to be a tuple you see or what you could do. 52 00:03:48,190 --> 00:03:52,960 If you want to improve that even further, you could use a dictionary. 53 00:03:53,020 --> 00:04:00,940 You could say feed is ft and inches as inches. 54 00:04:00,940 --> 00:04:04,780 You remember that with dictionaries we have pairs of keys and values. 55 00:04:04,780 --> 00:04:06,910 So the key here is the string. 56 00:04:06,910 --> 00:04:10,540 Its value is the number that the variable feeds contains. 57 00:04:10,540 --> 00:04:13,150 Then we have another pair of key and value. 58 00:04:13,150 --> 00:04:20,800 So if I get this functional, I define it in here in the console, execute it and then call it pause 59 00:04:20,950 --> 00:04:22,360 for 12. 60 00:04:22,450 --> 00:04:24,370 What we get is a dictionary. 61 00:04:24,370 --> 00:04:28,930 So now we have feeds and that is the value of feed and that's the value of inches. 62 00:04:28,930 --> 00:04:35,830 So that's a dictionary, which means you can access that value by providing here the name of its key 63 00:04:36,070 --> 00:04:41,650 feed as a string, and it gives you 4.0 and you can do the same four inches. 64 00:04:44,090 --> 00:04:45,080 12.0. 65 00:04:45,080 --> 00:04:53,990 So going back to the program in the F string here, we could say to get feet, we say pause. 66 00:04:54,020 --> 00:05:03,560 You call pause with feet and inches inside and then access feeds from that. 67 00:05:03,560 --> 00:05:08,420 Or even better, you could get that expression and do that outside. 68 00:05:08,420 --> 00:05:10,730 And you see past. 69 00:05:10,730 --> 00:05:11,900 Is that so? 70 00:05:11,900 --> 00:05:15,200 That should give you the dictionary as you saw here. 71 00:05:15,500 --> 00:05:17,360 So that gives the dictionary. 72 00:05:17,360 --> 00:05:17,960 Right. 73 00:05:18,890 --> 00:05:25,640 And then in here you see post and you extract feed. 74 00:05:25,670 --> 00:05:31,400 You need to use single quotes here since you have used double quotes outside the string. 75 00:05:31,400 --> 00:05:33,710 So for that string use single quotes. 76 00:05:33,710 --> 00:05:41,180 So again, that returns a dictionary, that dictionary and that extracts that feed value from the dictionary. 77 00:05:41,180 --> 00:05:47,090 Same, we do four interest post entries and that is equal to result. 78 00:05:47,090 --> 00:05:49,130 So result comes from convert. 79 00:05:49,130 --> 00:05:52,160 Now convert we need to work on this function as well. 80 00:05:52,550 --> 00:05:56,000 Convert now shouldn't be getting a string. 81 00:05:56,000 --> 00:06:00,770 It should get the units to convert, which is ft and inches. 82 00:06:00,770 --> 00:06:06,590 So it should get these as numbers and it shouldn't be doing any conversion from string to float. 83 00:06:06,590 --> 00:06:08,750 Just get numbers, return numbers. 84 00:06:08,750 --> 00:06:16,600 So here in convert then we say post feed to pass the feed value. 85 00:06:16,610 --> 00:06:19,400 The problem is this is highlighted in red. 86 00:06:19,400 --> 00:06:25,490 It says that this variable has not been defined, so this variable should be defined before it's used 87 00:06:25,490 --> 00:06:25,700 here. 88 00:06:25,700 --> 00:06:29,210 We are using it here, but we haven't defined it in this part. 89 00:06:29,210 --> 00:06:32,840 Therefore I just cut this from there and paste it up here. 90 00:06:32,840 --> 00:06:40,430 So we first get the feeds and inches and then we pass those feed and inches in here, converts again 91 00:06:41,180 --> 00:06:45,080 inches make a break line there, and that's the codes. 92 00:06:45,080 --> 00:06:47,030 Finally, let's run it. 93 00:06:47,210 --> 00:06:57,230 Feed on inches 311 and let's see, we've got an error bonus 13, line 17 which is in here. 94 00:06:57,350 --> 00:07:01,460 It says that function is not subscript double. 95 00:07:01,760 --> 00:07:02,060 Yeah. 96 00:07:02,060 --> 00:07:04,550 So here I did convert. 97 00:07:04,550 --> 00:07:06,200 I should have done post. 98 00:07:06,620 --> 00:07:07,610 Let's run again. 99 00:07:07,820 --> 00:07:16,850 310 Presenter Three feet and ten inches is equal to 116 kids can use the slide because the kid is higher 100 00:07:16,850 --> 00:07:17,990 than one metre. 101 00:07:18,670 --> 00:07:22,750 So that's how it should be working. 102 00:07:22,870 --> 00:07:23,920 That's a complete code. 103 00:07:23,920 --> 00:07:31,570 So again, to wrap it up, we get a string here and we want a function which does parsing of that string. 104 00:07:31,570 --> 00:07:34,060 We want to extract the numbers from that string. 105 00:07:34,060 --> 00:07:38,470 So it's better to have that parsing inside one single function. 106 00:07:38,470 --> 00:07:41,500 So functions that way are decoupled. 107 00:07:41,620 --> 00:07:43,480 That solves the problem. 108 00:07:43,480 --> 00:07:49,630 As I explained to you, that solves the problem of being able to access those things from that function. 109 00:07:49,630 --> 00:07:53,350 So we access those things and we use them in this f string here. 110 00:07:53,350 --> 00:07:58,600 And then the other function just does the conversion, and then we call that first function. 111 00:07:58,600 --> 00:08:05,770 And here in this line, force feeds inches, We pass that string as inputs, we get that dictionary 112 00:08:05,770 --> 00:08:06,640 as output. 113 00:08:06,640 --> 00:08:13,600 And then in here we use the feed value from that dictionary and the inches value from that dictionary 114 00:08:13,600 --> 00:08:17,680 to supply them to the convert function, which gets these two numbers. 115 00:08:17,680 --> 00:08:20,560 So those two numbers are converted into meters. 116 00:08:20,560 --> 00:08:23,800 Meters is returned here, therefore it is stored in result. 117 00:08:23,800 --> 00:08:30,040 And then we construct this f string and then in this if else conditional, we check if the result if 118 00:08:30,040 --> 00:08:34,510 meters is less than one and we print out different messages depending on that. 119 00:08:34,659 --> 00:08:39,400 So decouple your functions and decouple your output as well. 120 00:08:39,880 --> 00:08:47,170 And before I close this video, I cannot resist without making an analogy again with a cafe ordering 121 00:08:47,170 --> 00:08:51,100 example to illustrate your decoupling in another way. 122 00:08:51,100 --> 00:08:57,160 So when you go to the cafe and you order it to the barista, then the barista will give you the coffee. 123 00:08:57,160 --> 00:09:04,690 They will not put sugar inside the coffee or milk, but they may have a separate place there where you 124 00:09:04,690 --> 00:09:07,960 can go and put the sugar or the milk to your coffee. 125 00:09:07,960 --> 00:09:10,480 So they are decoupling the output. 126 00:09:10,480 --> 00:09:13,360 They don't want to give you the coffee plus the sugar inside. 127 00:09:13,360 --> 00:09:16,570 So then the coffee might not be usable. 128 00:09:16,570 --> 00:09:18,610 The same thing we did here. 129 00:09:18,610 --> 00:09:25,690 We return the number only, not the number with some extras on top of it, which can be unusable for 130 00:09:25,690 --> 00:09:28,210 other components in the program. 131 00:09:28,210 --> 00:09:30,220 So that's about decoupling output. 132 00:09:30,250 --> 00:09:37,990 Now, decoupling functions how it works in a goods cafe, you do the order to the barista, but then 133 00:09:37,990 --> 00:09:40,630 you pay the money to the cashier. 134 00:09:40,630 --> 00:09:45,220 So the cashier processes the payment as the barista processes the coffee. 135 00:09:45,220 --> 00:09:47,140 So here they have two functions. 136 00:09:47,140 --> 00:09:49,960 Each of them does something and does it good. 137 00:09:49,960 --> 00:09:53,680 Well, that at least happens in efficient cafes. 138 00:09:53,680 --> 00:10:00,430 So if you want to create quality programs, you also need you also want to decouple your functions. 139 00:10:00,460 --> 00:10:02,200 That's what I have for this lecture. 140 00:10:02,200 --> 00:10:04,930 I hope it makes sense and I'll talk to you later. 141 00:10:05,020 --> 00:10:05,620 Thanks.