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diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/1 - Lesson Overview - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/1 - Lesson Overview - lang_en_vs4.srt deleted file mode 100644 index bab48c0..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/1 - Lesson Overview - lang_en_vs4.srt +++ /dev/null @@ -1,71 +0,0 @@ -1 -00:00:00,140 --> 00:00:02,220 -In the previous lesson, we discussed agile - -2 -00:00:02,220 --> 00:00:05,689 -software development. Its principles and practices. And two - -3 -00:00:05,689 --> 00:00:10,060 -specific agile processes. XP and Scrub. In - -4 -00:00:10,060 --> 00:00:12,230 -this lesson, we will introduce a practice that - -5 -00:00:12,230 --> 00:00:15,020 -is of fundamental importance in the context - -6 -00:00:15,020 --> 00:00:20,120 -of agile software development. Software refactoring. Software refactoring - -7 -00:00:20,120 --> 00:00:22,030 -is the process of taking a program and - -8 -00:00:22,030 --> 00:00:25,040 -transforming it to make it better. That is, - -9 -00:00:25,040 --> 00:00:27,240 -to make it easier to understand, make it - -10 -00:00:27,240 --> 00:00:29,880 -more maintainable, and in general to improve its - -11 -00:00:29,880 --> 00:00:34,300 -design. Specifically, we will discuss what the refactoring - -12 -00:00:34,300 --> 00:00:37,680 -is and why it is important? When to perform - -13 -00:00:37,680 --> 00:00:40,980 -refactoring, and when not to perform refactoring? And - -14 -00:00:40,980 --> 00:00:44,520 -how to perform refactoring in a fully automated way, - -15 -00:00:44,520 --> 00:00:47,293 -using tools. We will also introduce the concept - -16 -00:00:47,293 --> 00:00:50,040 -of bad smells, where a bad smell, in software, - -17 -00:00:50,040 --> 00:00:53,323 -is the indication that there might be something wrong with - -18 -00:00:53,323 --> 00:00:56,890 -the code that might call for the application of refactoring. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/10 - Consolidate Conditional Expression Solution - lang_en_vs3.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/10 - Consolidate Conditional Expression Solution - lang_en_vs3.srt deleted file mode 100644 index 89f2722..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/10 - Consolidate Conditional Expression Solution - lang_en_vs3.srt +++ /dev/null @@ -1,55 +0,0 @@ -1 -00:00:00,080 --> 00:00:03,230 -So the resulting code will be like this. As you can see here, - -2 -00:00:03,230 --> 00:00:06,602 -now I don't have the conditionals any longer, but I just have a call to - -3 -00:00:06,602 --> 00:00:09,938 -this notEligibleForDisability method. And this makes the code so - -4 -00:00:09,938 --> 00:00:14,092 -much clearer, because if I just need to understand how disabilityAmount works, - -5 -00:00:14,092 --> 00:00:17,945 -I can clearly see there is an initial check that is actually checking whether - -6 -00:00:17,945 --> 00:00:22,030 -an employee's eligible for disabilities or not. And if the check is false, so - -7 -00:00:22,030 --> 00:00:26,180 -if the employee's eligible, then I'll just perform the rest of the computation. - -8 -00:00:26,180 --> 00:00:27,710 -Otherwise I'll simply return zero. - -9 -00:00:27,710 --> 00:00:30,500 -So if I don't need to understand the details of this check, - -10 -00:00:30,500 --> 00:00:33,630 -I can simply look at this method and understand it all. And if I need to look at - -11 -00:00:33,630 --> 00:00:36,990 -the details I can just go, and look at the implementation of this method, - -12 -00:00:36,990 --> 00:00:39,600 -and I will get exactly the same information that I have here. But I'm sort of - -13 -00:00:39,600 --> 00:00:43,220 -separating the concerns, and making the code overall more understandable, and - -14 -00:00:43,220 --> 00:00:46,160 -therefore more maintainable, which is the main goal of refactoring. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en-us_vs2.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en-us_vs2.srt deleted file mode 100644 index ef89eb8..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en-us_vs2.srt +++ /dev/null @@ -1,263 +0,0 @@ -1 -00:00:00,080 --> 00:00:02,740 -Let's now see a related refactoring, which is the - -2 -00:00:02,740 --> 00:00:06,200 -decompose conditional refactoring. What happens here is that in some - -3 -00:00:06,200 --> 00:00:08,980 -cases, the complexity of the conditional logic in a program - -4 -00:00:08,980 --> 00:00:12,040 -can make a method hard to read and understand. Specifically - -5 -00:00:12,040 --> 00:00:15,760 -we might have one or more particularly complex conditional - -6 -00:00:15,760 --> 00:00:18,580 -statements. And similar to what we discussed for the previous - -7 -00:00:18,580 --> 00:00:21,630 -refactoring, the conditional, if it's too complex, might tell you - -8 -00:00:21,630 --> 00:00:25,170 -what happens, but obscure why it happens. To address this - -9 -00:00:25,170 --> 00:00:27,520 -issue, you can do a similar thing to what we did in - -10 -00:00:27,520 --> 00:00:31,800 -the previous refactoring. You can transform the condition into a method and then - -11 -00:00:31,800 --> 00:00:35,260 -replace the condition with a call to that method. And if you give - -12 -00:00:35,260 --> 00:00:37,930 -the right name to the method, as we saw in the last example, - -13 -00:00:37,930 --> 00:00:41,730 -that can make the code much clearer and much easier to understand. In - -14 -00:00:41,730 --> 00:00:44,360 -addition here you can also do something else. Let's assume that those are - -15 -00:00:44,360 --> 00:00:47,430 -the then and else part of the conditional are complex. We can do - -16 -00:00:47,430 --> 00:00:50,180 -the same thing with them. So what we can do, we can modify - -17 -00:00:50,180 --> 00:00:53,570 -the then and else part of the conditional by extracting the corresponding - -18 -00:00:53,570 --> 00:00:57,070 -code, making also that one into a method, suitably naming the method, - -19 -00:00:57,070 --> 00:00:59,930 -and then having the call to the method only in the then - -20 -00:00:59,930 --> 00:01:03,540 -and else part of the conditional statement. So let's see how that works - -21 -00:01:03,540 --> 00:01:06,940 -with an example. Here we have the matter that computes some charge. - -22 -00:01:06,940 --> 00:01:10,350 -And it computes the charge based on some corrective uses of the date - -23 -00:01:10,350 --> 00:01:12,930 -that is provided as input, or it's imagined or is just, you - -24 -00:01:12,930 --> 00:01:15,410 -know, one of the fields in the class. So as you can see, - -25 -00:01:15,410 --> 00:01:18,140 -there is a conditional here that checks that if the - -26 -00:01:18,140 --> 00:01:21,535 -dates is before the beginning of the summer, so before summer - -27 -00:01:21,535 --> 00:01:25,180 -start. Or it's after the summer end. Then it compute - -28 -00:01:25,180 --> 00:01:29,152 -the charge using some winterRate. Otherwise, if we are in the - -29 -00:01:29,152 --> 00:01:32,288 -summer, it will compute the quantity, the charge using a - -30 -00:01:32,288 --> 00:01:35,440 -summerRate. And this is just a small example, so it might - -31 -00:01:35,440 --> 00:01:37,990 -not look that complex. But, you know, just project this on - -32 -00:01:37,990 --> 00:01:40,458 -more realistic code, on larger code. You can end up with - -33 -00:01:40,458 --> 00:01:43,656 -the conditions that are hard to understand. And even in this case, even - -34 -00:01:43,656 --> 00:01:45,944 -such a small piece of code, you have to kind of look at - -35 -00:01:45,944 --> 00:01:48,752 -the conditionals, figure out what does it mean for the date to be - -36 -00:01:48,752 --> 00:01:51,800 -before the summer start and after the summer end. We can make this much - -37 -00:01:51,800 --> 00:01:54,780 -clearer. So, how can we do it? By applying this refactoring as we - -38 -00:01:54,780 --> 00:01:56,190 -described. Let's see what happens when - -39 -00:01:56,190 --> 00:01:58,380 -I apply the decompose conditionals refactoring to - -40 -00:01:58,380 --> 00:02:01,530 -this method. The first thing I will do is to take this condition, - -41 -00:02:01,530 --> 00:02:05,640 -create a method that perform exactly the same check, give it a meaningful name. - -42 -00:02:05,640 --> 00:02:09,380 -In this case I called it notSummer, which is pretty self-explanatory, and then - -43 -00:02:09,380 --> 00:02:12,340 -replacing the condition with a call to that matter. As you can see - -44 -00:02:12,340 --> 00:02:15,230 -here, there's a clear improvement in the code, because here I just need - -45 -00:02:15,230 --> 00:02:17,810 -to look at this statement and I see right away that the check. What - -46 -00:02:17,810 --> 00:02:20,680 -the check is doing is just checking whether the date is in the - -47 -00:02:20,680 --> 00:02:24,320 -summer or not. So, much easier than having to interpret this condition. And - -48 -00:02:24,320 --> 00:02:26,910 -the second thing I do is to take the code that computes the - -49 -00:02:26,910 --> 00:02:28,600 -charge and also in this case, creating - -50 -00:02:28,600 --> 00:02:31,028 -suitable methods that compute the winterCharge and - -51 -00:02:31,028 --> 00:02:34,838 -the summerCharge. And I called them exactly winterCharge and summerCharge which - -52 -00:02:34,838 --> 00:02:38,278 -again is self explanatory. And then I replace this computation with - -53 -00:02:38,278 --> 00:02:40,710 -a call to that method. So again, when I look at - -54 -00:02:40,710 --> 00:02:43,280 -this code, I can clearly see that the charge is computed - -55 -00:02:43,280 --> 00:02:46,570 -using some sort of winterCharge calculation and then using some sort - -56 -00:02:46,570 --> 00:02:50,490 -of summerCharge calculation. And if I don't want to know how - -57 -00:02:50,490 --> 00:02:52,670 -this is exactly computed, that's all I need to know to - -58 -00:02:52,670 --> 00:02:56,100 -understand what this method does. Easier and faster than looking at - -59 -00:02:56,100 --> 00:02:57,970 -this method and figuring out what it does. And if - -60 -00:02:57,970 --> 00:02:59,950 -I need to look at the details, exactly like in the - -61 -00:02:59,950 --> 00:03:01,550 -previous case, I can just go and look at the - -62 -00:03:01,550 --> 00:03:04,170 -implementation of winterCharge and summerCharge. But I will be looking at - -63 -00:03:04,170 --> 00:03:06,980 -that in its specific context. So, without having to understand - -64 -00:03:06,980 --> 00:03:09,760 -everything at once. So in this way, you make it clear - -65 -00:03:09,760 --> 00:03:12,840 -both why you're doing something, because it is notSummer, and - -66 -00:03:12,840 --> 00:03:16,300 -what exactly you're doing. You're computing a winterCharge, or a summerCharge. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en_vs8.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en_vs8.srt deleted file mode 100644 index ef89eb8..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/11 - Decompose Conditionals - lang_en_vs8.srt +++ /dev/null @@ -1,263 +0,0 @@ -1 -00:00:00,080 --> 00:00:02,740 -Let's now see a related refactoring, which is the - -2 -00:00:02,740 --> 00:00:06,200 -decompose conditional refactoring. What happens here is that in some - -3 -00:00:06,200 --> 00:00:08,980 -cases, the complexity of the conditional logic in a program - -4 -00:00:08,980 --> 00:00:12,040 -can make a method hard to read and understand. Specifically - -5 -00:00:12,040 --> 00:00:15,760 -we might have one or more particularly complex conditional - -6 -00:00:15,760 --> 00:00:18,580 -statements. And similar to what we discussed for the previous - -7 -00:00:18,580 --> 00:00:21,630 -refactoring, the conditional, if it's too complex, might tell you - -8 -00:00:21,630 --> 00:00:25,170 -what happens, but obscure why it happens. To address this - -9 -00:00:25,170 --> 00:00:27,520 -issue, you can do a similar thing to what we did in - -10 -00:00:27,520 --> 00:00:31,800 -the previous refactoring. You can transform the condition into a method and then - -11 -00:00:31,800 --> 00:00:35,260 -replace the condition with a call to that method. And if you give - -12 -00:00:35,260 --> 00:00:37,930 -the right name to the method, as we saw in the last example, - -13 -00:00:37,930 --> 00:00:41,730 -that can make the code much clearer and much easier to understand. In - -14 -00:00:41,730 --> 00:00:44,360 -addition here you can also do something else. Let's assume that those are - -15 -00:00:44,360 --> 00:00:47,430 -the then and else part of the conditional are complex. We can do - -16 -00:00:47,430 --> 00:00:50,180 -the same thing with them. So what we can do, we can modify - -17 -00:00:50,180 --> 00:00:53,570 -the then and else part of the conditional by extracting the corresponding - -18 -00:00:53,570 --> 00:00:57,070 -code, making also that one into a method, suitably naming the method, - -19 -00:00:57,070 --> 00:00:59,930 -and then having the call to the method only in the then - -20 -00:00:59,930 --> 00:01:03,540 -and else part of the conditional statement. So let's see how that works - -21 -00:01:03,540 --> 00:01:06,940 -with an example. Here we have the matter that computes some charge. - -22 -00:01:06,940 --> 00:01:10,350 -And it computes the charge based on some corrective uses of the date - -23 -00:01:10,350 --> 00:01:12,930 -that is provided as input, or it's imagined or is just, you - -24 -00:01:12,930 --> 00:01:15,410 -know, one of the fields in the class. So as you can see, - -25 -00:01:15,410 --> 00:01:18,140 -there is a conditional here that checks that if the - -26 -00:01:18,140 --> 00:01:21,535 -dates is before the beginning of the summer, so before summer - -27 -00:01:21,535 --> 00:01:25,180 -start. Or it's after the summer end. Then it compute - -28 -00:01:25,180 --> 00:01:29,152 -the charge using some winterRate. Otherwise, if we are in the - -29 -00:01:29,152 --> 00:01:32,288 -summer, it will compute the quantity, the charge using a - -30 -00:01:32,288 --> 00:01:35,440 -summerRate. And this is just a small example, so it might - -31 -00:01:35,440 --> 00:01:37,990 -not look that complex. But, you know, just project this on - -32 -00:01:37,990 --> 00:01:40,458 -more realistic code, on larger code. You can end up with - -33 -00:01:40,458 --> 00:01:43,656 -the conditions that are hard to understand. And even in this case, even - -34 -00:01:43,656 --> 00:01:45,944 -such a small piece of code, you have to kind of look at - -35 -00:01:45,944 --> 00:01:48,752 -the conditionals, figure out what does it mean for the date to be - -36 -00:01:48,752 --> 00:01:51,800 -before the summer start and after the summer end. We can make this much - -37 -00:01:51,800 --> 00:01:54,780 -clearer. So, how can we do it? By applying this refactoring as we - -38 -00:01:54,780 --> 00:01:56,190 -described. Let's see what happens when - -39 -00:01:56,190 --> 00:01:58,380 -I apply the decompose conditionals refactoring to - -40 -00:01:58,380 --> 00:02:01,530 -this method. The first thing I will do is to take this condition, - -41 -00:02:01,530 --> 00:02:05,640 -create a method that perform exactly the same check, give it a meaningful name. - -42 -00:02:05,640 --> 00:02:09,380 -In this case I called it notSummer, which is pretty self-explanatory, and then - -43 -00:02:09,380 --> 00:02:12,340 -replacing the condition with a call to that matter. As you can see - -44 -00:02:12,340 --> 00:02:15,230 -here, there's a clear improvement in the code, because here I just need - -45 -00:02:15,230 --> 00:02:17,810 -to look at this statement and I see right away that the check. What - -46 -00:02:17,810 --> 00:02:20,680 -the check is doing is just checking whether the date is in the - -47 -00:02:20,680 --> 00:02:24,320 -summer or not. So, much easier than having to interpret this condition. And - -48 -00:02:24,320 --> 00:02:26,910 -the second thing I do is to take the code that computes the - -49 -00:02:26,910 --> 00:02:28,600 -charge and also in this case, creating - -50 -00:02:28,600 --> 00:02:31,028 -suitable methods that compute the winterCharge and - -51 -00:02:31,028 --> 00:02:34,838 -the summerCharge. And I called them exactly winterCharge and summerCharge which - -52 -00:02:34,838 --> 00:02:38,278 -again is self explanatory. And then I replace this computation with - -53 -00:02:38,278 --> 00:02:40,710 -a call to that method. So again, when I look at - -54 -00:02:40,710 --> 00:02:43,280 -this code, I can clearly see that the charge is computed - -55 -00:02:43,280 --> 00:02:46,570 -using some sort of winterCharge calculation and then using some sort - -56 -00:02:46,570 --> 00:02:50,490 -of summerCharge calculation. And if I don't want to know how - -57 -00:02:50,490 --> 00:02:52,670 -this is exactly computed, that's all I need to know to - -58 -00:02:52,670 --> 00:02:56,100 -understand what this method does. Easier and faster than looking at - -59 -00:02:56,100 --> 00:02:57,970 -this method and figuring out what it does. And if - -60 -00:02:57,970 --> 00:02:59,950 -I need to look at the details, exactly like in the - -61 -00:02:59,950 --> 00:03:01,550 -previous case, I can just go and look at the - -62 -00:03:01,550 --> 00:03:04,170 -implementation of winterCharge and summerCharge. But I will be looking at - -63 -00:03:04,170 --> 00:03:06,980 -that in its specific context. So, without having to understand - -64 -00:03:06,980 --> 00:03:09,760 -everything at once. So in this way, you make it clear - -65 -00:03:09,760 --> 00:03:12,840 -both why you're doing something, because it is notSummer, and - -66 -00:03:12,840 --> 00:03:16,300 -what exactly you're doing. You're computing a winterCharge, or a summerCharge. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/12 - Extract Class - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/12 - Extract Class - lang_en_vs4.srt deleted file mode 100644 index 07c93ed..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/12 - Extract Class - lang_en_vs4.srt +++ /dev/null @@ -1,99 +0,0 @@ -1 -00:00:00,100 --> 00:00:02,890 -We are now going to talk about the extract class refactoring. When a - -2 -00:00:02,890 --> 00:00:06,040 -softer system evolves, we might end up with classes that really do the - -3 -00:00:06,040 --> 00:00:09,210 -work of more than one class because we keep adding functionality to - -4 -00:00:09,210 --> 00:00:11,010 -the class. Therefore also they're too - -5 -00:00:11,010 --> 00:00:13,160 -big, too complicated. In particular, we might - -6 -00:00:13,160 --> 00:00:15,250 -end up with a class that is doing the work of two - -7 -00:00:15,250 --> 00:00:18,890 -classes. Typical examples are classes with many methods and quite a lot of - -8 -00:00:18,890 --> 00:00:22,520 -data, quite a lot of fields. In this case, it's normally good idea - -9 -00:00:22,520 --> 00:00:25,120 -to split the class into two, so what you will do, you will - -10 -00:00:25,120 --> 00:00:28,700 -create a new class and move there the relevant fields and methods from - -11 -00:00:28,700 --> 00:00:31,700 -the original class. So as to have two classes, each one implementing a - -12 -00:00:31,700 --> 00:00:34,900 -piece of the functionality. Let's look at an example. In this case we're - -13 -00:00:34,900 --> 00:00:38,850 -going to use a UML like representation for the class. We have this class Person - -14 -00:00:38,850 --> 00:00:41,769 -that ends up representing also a phone number. And imagine that we add - -15 -00:00:41,769 --> 00:00:44,500 -up these pieces, you know, a little bit at the time so we end - -16 -00:00:44,500 --> 00:00:47,430 -up with something that really is doing the job of the person and - -17 -00:00:47,430 --> 00:00:50,490 -of the phone number. So what we can do, we can actually do exactly - -18 -00:00:50,490 --> 00:00:52,650 -what we described here. We split this class - -19 -00:00:52,650 --> 00:00:55,470 -into a Person class, and the Phone Number class. - -20 -00:00:55,470 --> 00:00:57,440 -And then we establish a use relation, so we - -21 -00:00:57,440 --> 00:00:59,470 -have a reference of the phone number class into - -22 -00:00:59,470 --> 00:01:01,960 -this class. And by separating the telephone number behavior - -23 -00:01:01,960 --> 00:01:04,680 -into its own class, I once more improved the - -24 -00:01:04,680 --> 00:01:06,980 -structure of the code, because now I have classes - -25 -00:01:06,980 --> 00:01:09,070 -that are more cohesive, and do exactly one thing. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/13 - Inline Class - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/13 - Inline Class - lang_en_vs4.srt deleted file mode 100644 index a7f7f2f..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/13 - Inline Class - lang_en_vs4.srt +++ /dev/null @@ -1,75 +0,0 @@ -1 -00:00:00,150 --> 00:00:03,825 -This new refactoring called inline class is the reverse of the extract class - -2 -00:00:03,825 --> 00:00:06,700 -refactoring. And know that this is kind of a general situation in the - -3 -00:00:06,700 --> 00:00:09,500 -sense that it is often the case that the refactoring also has a - -4 -00:00:09,500 --> 00:00:11,480 -reverse refactoring that does exactly the - -5 -00:00:11,480 --> 00:00:13,202 -opposite. So basically, un-dos, in a sense, - -6 -00:00:13,202 --> 00:00:16,830 -the operation of the other refactoring. In this case, the motivation for the - -7 -00:00:16,830 --> 00:00:19,760 -refactoring is that during system evolution, we might end up with one or - -8 -00:00:19,760 --> 00:00:22,530 -more classes that do not do much. In this case what you want - -9 -00:00:22,530 --> 00:00:25,350 -to do is to take the class that is not doing that much and - -10 -00:00:25,350 --> 00:00:28,740 -move its features into another class. And then delete the original class. - -11 -00:00:28,740 --> 00:00:31,010 -So lets use an example similar to the one we've used for - -12 -00:00:31,010 --> 00:00:34,000 -the previous refactoring to illustrate how this works. Here we have in - -13 -00:00:34,000 --> 00:00:37,750 -this case, two classes, person and office. And the person class is - -14 -00:00:37,750 --> 00:00:40,720 -using the office class, but this latter class, the office class, only - -15 -00:00:40,720 --> 00:00:44,000 -contains a phone number. So it doesn't really do that much. What - -16 -00:00:44,000 --> 00:00:47,020 -we can do is therefore to fold the office class into the - -17 -00:00:47,020 --> 00:00:50,470 -person class, by simply moving its only field into the class. And so - -18 -00:00:50,470 --> 00:00:53,260 -the result will be this person class that also contains the information - -19 -00:00:53,260 --> 00:00:56,600 -about the office number, and overall a simpler design for the code. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/14 - Extract Method - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/14 - Extract Method - lang_en_vs4.srt deleted file mode 100644 index 88769e0..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/14 - Extract Method - lang_en_vs4.srt +++ /dev/null @@ -1,163 +0,0 @@ -1 -00:00:00,060 --> 00:00:02,406 -The next re-factoring which is also the last one that we'll - -2 -00:00:02,406 --> 00:00:05,640 -see, extract method is one of the most commonly used re-factoring. As - -3 -00:00:05,640 --> 00:00:09,080 -it is applicable in many, many situations. The starting point is - -4 -00:00:09,080 --> 00:00:12,720 -a method that is too long and contains cohesive code fragments, that - -5 -00:00:12,720 --> 00:00:16,180 -really serve a single very specific purpose. So we start from - -6 -00:00:16,180 --> 00:00:19,270 -a cohesive code fragment in a large method. What we can do - -7 -00:00:19,270 --> 00:00:22,370 -in this case, is to create a method using that code fragment. - -8 -00:00:22,370 --> 00:00:25,620 -And then replacing the code fragment with a call to that method. - -9 -00:00:25,620 --> 00:00:28,390 -Let's look at this with an example. Here over this method called - -10 -00:00:28,390 --> 00:00:31,070 -print owing, and what it does, imagine that it does a lot - -11 -00:00:31,070 --> 00:00:33,850 -of operations here that I'm just not listing, and then it's got - -12 -00:00:33,850 --> 00:00:37,620 -a set of print statements. That are just printing a lot of details - -13 -00:00:37,620 --> 00:00:41,280 -about the owing information. And then again, a lot of code after - -14 -00:00:41,280 --> 00:00:44,270 -that. So what I could do in this case to simplify. The - -15 -00:00:44,270 --> 00:00:47,940 -method is to transform this set of statements. They are cohesive in - -16 -00:00:47,940 --> 00:00:51,120 -the sense that they do just one thing, they just print these details - -17 -00:00:51,120 --> 00:00:53,890 -into a method, and then I had, replace the statements with a - -18 -00:00:53,890 --> 00:00:56,740 -call to that method. Which is actually something similar to what we did - -19 -00:00:56,740 --> 00:00:59,900 -as part of some the previous re-factoring's. Here I'm showing the result. - -20 -00:00:59,900 --> 00:01:02,770 -So here is the method that I extracted. As you can see. It - -21 -00:01:02,770 --> 00:01:05,790 -contains the code that was previously here. I give you the meaningful - -22 -00:01:05,790 --> 00:01:09,080 -name, I called it printDetails so it's clear what it does. And now - -23 -00:01:09,080 --> 00:01:12,820 -the print owning method is simpler. Because I still have the remaining code - -24 -00:01:12,820 --> 00:01:17,200 -the one I didn't touch. But now this potentially long list of details. - -25 -00:01:17,200 --> 00:01:20,560 -Of prints, of details is not replaced by a single method code. - -26 -00:01:20,560 --> 00:01:23,550 -So a gain similar to the previous refactorings that we saw. If - -27 -00:01:23,550 --> 00:01:26,370 -we just look at the printing method, it's very easy to figure - -28 -00:01:26,370 --> 00:01:29,490 -out what this part does. Oh, print some details. And once more I - -29 -00:01:29,490 --> 00:01:33,060 -really want to stress this. If you don't care about how, this - -30 -00:01:33,060 --> 00:01:36,350 -is implemented and knowing that this print some details is enough. Then - -31 -00:01:36,350 --> 00:01:38,980 -you're done. You don't need to understand anything more. It's clear, it's - -32 -00:01:38,980 --> 00:01:42,430 -self explanatory. And if you'll need to look at what print details does, - -33 -00:01:42,430 --> 00:01:44,390 -you just go and look at print details. And you look at - -34 -00:01:44,390 --> 00:01:47,280 -it in isolation. So it's easier to understand what this does without having - -35 -00:01:47,280 --> 00:01:49,640 -to think the rest of the code. So once more the color we - -36 -00:01:49,640 --> 00:01:52,740 -factor in is just to improve your design, made the code more readable - -37 -00:01:52,740 --> 00:01:56,020 -Make the code more maintainable. And also keep in mind all of these, - -38 -00:01:56,020 --> 00:01:59,080 -are kind of small examples. You also always have to think about the - -39 -00:01:59,080 --> 00:02:02,560 -effect that this can have on larger codebases. It can really improve a - -40 -00:02:02,560 --> 00:02:05,280 -lot. The understandabililty, and maintainability of - -41 -00:02:05,280 --> 00:02:07,220 -your code. So in general, it's design. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/15 - Refactoring Demo - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/15 - Refactoring Demo - lang_en_vs4.srt deleted file mode 100644 index 0559c88..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/15 - Refactoring Demo - lang_en_vs4.srt +++ /dev/null @@ -1,599 +0,0 @@ -1 -00:00:00,090 --> 00:00:03,110 -So now we saw, this set of re-factoring's. They're nice, but - -2 -00:00:03,110 --> 00:00:06,260 -how can we actually perform re-factoring's? In some cases you'll have to - -3 -00:00:06,260 --> 00:00:08,430 -do it by hand. And you'll do it in that case in - -4 -00:00:08,430 --> 00:00:10,880 -small steps, so that you can check at every step that you - -5 -00:00:10,880 --> 00:00:14,180 -didn't introduce any area. But there's also many cases in which at - -6 -00:00:14,180 --> 00:00:17,640 -least for the more standard re-factoring's, you can just apply, you can - -7 -00:00:17,640 --> 00:00:21,530 -just use a tool that actually supports re-factoring. I'm going to show - -8 -00:00:21,530 --> 00:00:24,550 -you how that works, into a specific ID, Eclipse through a demo. - -9 -00:00:26,120 --> 00:00:28,425 -To show you how Eclipse, can help in performing - -10 -00:00:28,425 --> 00:00:31,880 -re-factoring, in an automated way, I just opened the Eclipse - -11 -00:00:31,880 --> 00:00:35,050 -editor and I maximized it. So that we can look - -12 -00:00:35,050 --> 00:00:36,810 -at the code more clearly. And as you can see - -13 -00:00:36,810 --> 00:00:39,551 -here, I have this class. It's called Re-factorable, it's a - -14 -00:00:39,551 --> 00:00:43,550 -pretty indicative name. And what we're going to do, we're going to - -15 -00:00:43,550 --> 00:00:47,840 -try to apply the extract method re-factoring to this class. - -16 -00:00:47,840 --> 00:00:51,060 -And in particular, to parts of this print owing method. - -17 -00:00:51,060 --> 00:00:54,090 -So this is a matter than will print owing's, - -18 -00:00:54,090 --> 00:00:56,160 -as the name says. And it will do several things - -19 -00:00:56,160 --> 00:00:59,180 -such as, for example, printing a banner first, then - -20 -00:00:59,180 --> 00:01:03,650 -calculating the outstanding debts, and then printing some details. So - -21 -00:01:03,650 --> 00:01:06,980 -the starting point for an extract method re-fractoring, is - -22 -00:01:06,980 --> 00:01:10,650 -the identification of some cohesive code fragment. And here, for - -23 -00:01:10,650 --> 00:01:12,970 -instance, we can see that, if we can see there, - -24 -00:01:12,970 --> 00:01:16,350 -these three print statements. They are basically printing some banner, - -25 -00:01:16,350 --> 00:01:18,530 -for the method. And I also put a comment here - -26 -00:01:18,530 --> 00:01:21,160 -just to make that even more explicit. So this is a - -27 -00:01:21,160 --> 00:01:23,970 -perfect case in which we might want to just extract - -28 -00:01:23,970 --> 00:01:27,220 -this part, create an independent method, so that we can make - -29 -00:01:27,220 --> 00:01:31,410 -the code more readable and maintainable. So I select, the - -30 -00:01:31,410 --> 00:01:33,320 -part of the code, that I want to put in my - -31 -00:01:33,320 --> 00:01:37,080 -method. I invoke the contextual menu, and as you can see - -32 -00:01:37,080 --> 00:01:41,287 -there is a re-factor entry here. Here are some re-factoring's [UNKNOWN], - -33 -00:01:41,287 --> 00:01:45,039 -re-factoring's that I can apply, and I'm going to select extract - -34 -00:01:45,039 --> 00:01:48,120 -method. When I do that, Eclipse is going to ask me to - -35 -00:01:48,120 --> 00:01:51,610 -specify a method name. I'll just call this one print - -36 -00:01:51,610 --> 00:01:54,260 -banner. And as you can see, as soon as I do - -37 -00:01:54,260 --> 00:01:57,310 -that, Eclipse will show me the preview, for the method - -38 -00:01:57,310 --> 00:02:01,010 -that will be generated. I'm going to leave the access modifier. To - -39 -00:02:01,010 --> 00:02:03,290 -public and I'm not going to change anything else. So, - -40 -00:02:03,290 --> 00:02:07,760 -now when I click Ok. As you can see Eclipse modified - -41 -00:02:07,760 --> 00:02:10,669 -my code so that now I have the Print Banner method - -42 -00:02:10,669 --> 00:02:14,050 -down here that does exactly what that piece of code was doing - -43 -00:02:14,050 --> 00:02:16,090 -before. And I just have an invocation of the Print Banner - -44 -00:02:16,090 --> 00:02:19,440 -method, up here, where the code was before. And of course, this - -45 -00:02:19,440 --> 00:02:21,830 -is something that we could have done by hand. It's pretty - -46 -00:02:21,830 --> 00:02:25,480 -easy to do, but it's even easier, to do it using Eclipse's - -47 -00:02:25,480 --> 00:02:29,040 -capabilities. And this will become even more apparent, when we consider slightly - -48 -00:02:29,040 --> 00:02:32,866 -more complex case. So here, if we look at this piece of - -49 -00:02:32,866 --> 00:02:35,234 -code for instance, we can that see this code - -50 -00:02:35,234 --> 00:02:38,264 -prints some details, about the always. And the reason - -51 -00:02:38,264 --> 00:02:41,351 -why this case is likely more complicated, is because - -52 -00:02:41,351 --> 00:02:45,210 -this code needs to know about the value of outstanding. - -53 -00:02:45,210 --> 00:02:49,130 -And whereas that underscore name, is a member of - -54 -00:02:49,130 --> 00:02:51,150 -the class, and therefore will be available to the - -55 -00:02:51,150 --> 00:02:55,110 -method. Outstanding is a locker variable, so a method - -56 -00:02:55,110 --> 00:02:58,310 -different from print, oh it wouldn't know anything about outstanding. - -57 -00:02:58,310 --> 00:03:00,070 -So let's see what happens when we try to apply - -58 -00:03:00,070 --> 00:03:03,460 -a re-factoring for this code. So we go again here - -59 -00:03:03,460 --> 00:03:06,410 -to the re-factor menu, we select extract method, we will - -60 -00:03:06,410 --> 00:03:10,080 -pick a name again. So let's call it [SOUND] print details, - -61 -00:03:10,080 --> 00:03:12,660 -since this is what the code does. And as you - -62 -00:03:12,660 --> 00:03:17,270 -can see here, Eclipse was able to figure out, that outstanding - -63 -00:03:17,270 --> 00:03:20,290 -has to be a parameter, of this method. So if - -64 -00:03:20,290 --> 00:03:23,340 -you look at the signature here, this will be very clear. - -65 -00:03:23,340 --> 00:03:26,270 -So outstanding has to be passed to the matter because - -66 -00:03:26,270 --> 00:03:29,230 -it's a locker variable of the print owing method. so - -67 -00:03:29,230 --> 00:03:32,600 -it will not be visible to the other methods otherwise. - -68 -00:03:32,600 --> 00:03:34,990 -So since eclipse figured it out, all I have to do, - -69 -00:03:34,990 --> 00:03:37,630 -is to press Ok. And at this point what I - -70 -00:03:37,630 --> 00:03:41,280 -will have here is my new method, for in details - -71 -00:03:41,280 --> 00:03:45,140 -that takes outstanding as a parameter. And does exactly what - -72 -00:03:45,140 --> 00:03:48,880 -the code was doing before. And here, where the code was, - -73 -00:03:48,880 --> 00:03:51,630 -I will have my print details invocation, with outstanding - -74 -00:03:51,630 --> 00:03:54,930 -as a parameter. So now, let's continue to extract methods. - -75 -00:03:54,930 --> 00:03:58,470 -And let's look at a even more complex case. which - -76 -00:03:58,470 --> 00:04:01,550 -is, the one involving this piece of code. So this - -77 -00:04:01,550 --> 00:04:03,900 -piece of code, as you can see, will calculate - -78 -00:04:03,900 --> 00:04:07,820 -the value of the outstanding debt. Will calculate the owing's, - -79 -00:04:07,820 --> 00:04:09,600 -and the way in which it does that, is by - -80 -00:04:09,600 --> 00:04:14,080 -considering all the orders, that are part of this enumeration. - -81 -00:04:14,080 --> 00:04:16,519 -That is the declared here, and it will - -82 -00:04:16,519 --> 00:04:20,769 -compute for each one, of these orders, the amount, - -83 -00:04:20,769 --> 00:04:23,520 -and then added to outstanding. So what is the - -84 -00:04:23,520 --> 00:04:26,160 -additional complication here? Well, the additional complication here is - -85 -00:04:26,160 --> 00:04:29,520 -that this code needs to know, not only - -86 -00:04:29,520 --> 00:04:33,220 -about outstanding. It also needs to know, about this - -87 -00:04:33,220 --> 00:04:36,160 -enumeration, because this one is also a local variable. - -88 -00:04:36,160 --> 00:04:39,140 -And in addition to that, this code also has - -89 -00:04:39,140 --> 00:04:43,280 -some side effects. So outstanding, is modified as a - -90 -00:04:43,280 --> 00:04:46,600 -consequence of the execution of this code. So how can - -91 -00:04:46,600 --> 00:04:49,120 -we do that in the extracted method? Well lets - -92 -00:04:49,120 --> 00:04:51,000 -see what the clips will do and what the clips - -93 -00:04:51,000 --> 00:04:53,950 -will suggest. It will try to again re-factor this - -94 -00:04:53,950 --> 00:04:58,030 -code and extract the method. In this case as you - -95 -00:04:58,030 --> 00:05:01,160 -can see. The clips does two things. First of all, - -96 -00:05:01,160 --> 00:05:04,180 -it figures out as before, that there are some parameters, - -97 -00:05:04,180 --> 00:05:07,650 -that are needed for this method to operate correctly. The - -98 -00:05:07,650 --> 00:05:11,600 -enumeration e, as we said, and the outstanding variable. In - -99 -00:05:11,600 --> 00:05:14,880 -addition, if you look at the method signature Eclipse will - -100 -00:05:14,880 --> 00:05:17,490 -also figure out that this method has to return, a - -101 -00:05:17,490 --> 00:05:21,530 -double value. So what does this value correspond to? This - -102 -00:05:21,530 --> 00:05:24,700 -value corresponds to a new value of outstanding. So if - -103 -00:05:24,700 --> 00:05:27,490 -we, give a name to this method, so we just - -104 -00:05:27,490 --> 00:05:29,620 -use the name, [SOUND] that I put in the comment - -105 -00:05:29,620 --> 00:05:33,510 -over there. We click Ok, and this will create - -106 -00:05:33,510 --> 00:05:36,560 -a method by extracting the code. And here, where the - -107 -00:05:36,560 --> 00:05:39,100 -method used to be, we will have that the - -108 -00:05:39,100 --> 00:05:43,169 -value of outstanding is updated. Based on the return value - -109 -00:05:43,169 --> 00:05:46,260 -of calculate outstanding. So in the end if we - -110 -00:05:46,260 --> 00:05:48,730 -look at this code, you can see that if we - -111 -00:05:48,730 --> 00:05:51,980 -just focus, on this code it's very easy to - -112 -00:05:51,980 --> 00:05:55,150 -understand what it does. It prints the banner, it calculates - -113 -00:05:55,150 --> 00:05:59,180 -an outstanding value, and then it prints some details. And - -114 -00:05:59,180 --> 00:06:01,520 -in case we don't care, as I said before, about the - -115 -00:06:01,520 --> 00:06:04,840 -details of what these methods do, we're done. And if we - -116 -00:06:04,840 --> 00:06:07,740 -care about the details we can look at each matter individually. - -117 -00:06:07,740 --> 00:06:10,580 -And get exactly the same information that we got before, - -118 -00:06:10,580 --> 00:06:13,650 -in a sort of a separation of concerns kind of way, - -119 -00:06:13,650 --> 00:06:16,420 -by focusing on one problem at a time. So now let - -120 -00:06:16,420 --> 00:06:19,345 -me do one last thing. So let me modify the code, - -121 -00:06:19,345 --> 00:06:23,170 -slightly. So i'm going to go back, to the version of - -122 -00:06:23,170 --> 00:06:25,610 -the code before re-factoring. So this is what we had. - -123 -00:06:25,610 --> 00:06:32,480 -And I'm going to add, an additional variable here, [SOUND] called count, - -124 -00:06:32,480 --> 00:06:38,870 -which I initialize to zero. Here I'm going to increase, [SOUND] - -125 -00:06:38,870 --> 00:06:41,360 -the value of count at every iteration. And - -126 -00:06:41,360 --> 00:06:44,570 -finally, here I'm going to print out the value - -127 -00:06:44,570 --> 00:06:50,130 -of count. Okay, now that I have this code up. So let's imagine that I - -128 -00:06:50,130 --> 00:06:55,665 -want to, again as I did before, extract this matter. So, I'm going to - -129 -00:06:55,665 --> 00:06:58,430 -give you a second. Have a look at this and see, if you see - -130 -00:06:58,430 --> 00:07:02,170 -any problem with that. Feel free to stop the video, if you need more time. - -131 -00:07:07,350 --> 00:07:11,440 -So the problem here is that I have two side effects. - -132 -00:07:11,440 --> 00:07:14,820 -Both outstanding and count are modified. And therefore it's not really - -133 -00:07:14,820 --> 00:07:19,600 -possible to extract this method, and preserve the semantics of this - -134 -00:07:19,600 --> 00:07:23,260 -code. Let's see if Eclipse will be able to figure that out. - -135 -00:07:26,130 --> 00:07:28,950 -And it does. If we try to extract the matter here, - -136 -00:07:28,950 --> 00:07:32,250 -you'll tell us that's an ambiguous return value. The selected block - -137 -00:07:32,250 --> 00:07:35,800 -contains more than one assignment to look at variables. And the - -138 -00:07:35,800 --> 00:07:40,170 -affected variables are outstanding, just a Double and Count which is - -139 -00:07:40,170 --> 00:07:44,780 -an integer. So it will refuse to extract the method. So - -140 -00:07:44,780 --> 00:07:46,470 -at this point if we wanted to do that we have - -141 -00:07:46,470 --> 00:07:48,650 -we'll have to do the re-factoring a different way, but I - -142 -00:07:48,650 --> 00:07:51,110 -don't really want to get there. I want to conclude here, - -143 -00:07:51,110 --> 00:07:53,440 -and I hope this this little demo helped you - -144 -00:07:53,440 --> 00:07:55,310 -realize how useful it can be to use an - -145 -00:07:55,310 --> 00:07:58,270 -id that supports re-factoring that can automate this important - -146 -00:07:58,270 --> 00:08:00,160 -task. And I also encourage you to try to play - -147 -00:08:00,160 --> 00:08:03,170 -with this, and try to use different re-factoring's, on - -148 -00:08:03,170 --> 00:08:05,480 -your code. So as to get familiar with the kind - -149 -00:08:05,480 --> 00:08:08,060 -of re-factoring's that are supported by the ID. And - -150 -00:08:08,060 --> 00:08:10,800 -also with the re-factoring's themselves and how should be used. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/16 - Extract Method Refactoring Quiz - lang_en_vs5.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/16 - Extract Method Refactoring Quiz - lang_en_vs5.srt deleted file mode 100644 index 07f5e44..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/16 - Extract Method Refactoring Quiz - lang_en_vs5.srt +++ /dev/null @@ -1,31 +0,0 @@ -1 -00:00:00,160 --> 00:00:02,580 -After the demo I would like to have a little quiz - -2 -00:00:02,580 --> 00:00:05,430 -about the extract method refactoring. And I would like to ask you - -3 -00:00:05,430 --> 00:00:08,910 -when is it appropriate to apply the extract method refactoring. Here I - -4 -00:00:08,910 --> 00:00:11,890 -have a set of possible scenarios. First one is when there is - -5 -00:00:11,890 --> 00:00:14,730 -duplicated code in two or more methods. When a class is too - -6 -00:00:14,730 --> 00:00:17,730 -large. When the names of two classes are too similar. Or when - -7 -00:00:17,730 --> 00:00:20,840 -a method is highly coupled with a class other than the one - -8 -00:00:20,840 --> 00:00:24,370 -where it is defined. So as usual, please mark all that apply. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/17 - Extract Method Refactoring Quiz Solution - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/17 - Extract Method Refactoring Quiz Solution - lang_en_vs4.srt deleted file mode 100644 index 6545de0..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/17 - Extract Method Refactoring Quiz Solution - lang_en_vs4.srt +++ /dev/null @@ -1,83 +0,0 @@ -1 -00:00:00,110 --> 00:00:03,000 -The first scenario is the typical case in which it is - -2 -00:00:03,000 --> 00:00:07,040 -recommended to use the extract method refactoring, when there is duplicated code - -3 -00:00:07,040 --> 00:00:09,190 -in two or more methods and we want to take this - -4 -00:00:09,190 --> 00:00:12,420 -code and factor is out, and basically have the two methods called - -5 -00:00:12,420 --> 00:00:14,960 -a third method, which is the one we create using the - -6 -00:00:14,960 --> 00:00:18,060 -refactoring. When a class is too large, normally we don't want to - -7 -00:00:18,060 --> 00:00:21,330 -apply the extract. Extract method. Instead, in this cases, it is - -8 -00:00:21,330 --> 00:00:22,900 -usually more appropriate to use the - -9 -00:00:22,900 --> 00:00:26,420 -extract class or extract subclass refactorings. - -10 -00:00:26,420 --> 00:00:29,750 -Analogously, when the names of two classes are too similar, extracting a - -11 -00:00:29,750 --> 00:00:32,729 -method will normally not help much. And all we need to do - -12 -00:00:32,729 --> 00:00:35,810 -in case having too similar names is actually a problem. Is to - -13 -00:00:35,810 --> 00:00:39,600 -rename one of the two classes, or both, if we wish. Finally, - -14 -00:00:39,600 --> 00:00:42,530 -it is definitely appropriate to apply the extract method of refactoring in - -15 -00:00:42,530 --> 00:00:45,900 -cases in which a method is highly coupled with a class other - -16 -00:00:45,900 --> 00:00:48,330 -than the one where it is defined. In this case, which we - -17 -00:00:48,330 --> 00:00:51,740 -will discuss also later in the lesson, the extract method of refactoring - -18 -00:00:51,740 --> 00:00:55,710 -allows us to extract part of the metal to With the other class. - -19 -00:00:55,710 --> 00:00:58,690 -Then we can take the matter that we just extracted and move it - -20 -00:00:58,690 --> 00:01:01,880 -to the class where it actually belongs. So the extract method is one - -21 -00:01:01,880 --> 00:01:05,560 -of the two refactorings that it is appropriate to apply in these cases. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/18 - Refactoring Risks - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/18 - Refactoring Risks - lang_en_vs4.srt deleted file mode 100644 index 0aae00c..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/18 - Refactoring Risks - lang_en_vs4.srt +++ /dev/null @@ -1,143 +0,0 @@ -1 -00:00:00,150 --> 00:00:02,520 -Now that we saw a number of refactorings, we also saw - -2 -00:00:02,520 --> 00:00:05,950 -how refactorings can be performed automatically within an ID, I'd like - -3 -00:00:05,950 --> 00:00:09,230 -to make you aware of some risks involved with the user - -4 -00:00:09,230 --> 00:00:12,510 -refactorings. Refactorings are a very powerful tool, but you also have to - -5 -00:00:12,510 --> 00:00:15,820 -be careful, first of all when you do more complex refactorings, - -6 -00:00:15,820 --> 00:00:18,540 -you may also introduce subtle faults. What, we don't really call - -7 -00:00:18,540 --> 00:00:21,040 -regression errors. You might change something in the class. You might - -8 -00:00:21,040 --> 00:00:23,140 -think that that's a behavior preserving - -9 -00:00:23,140 --> 00:00:25,200 -transformation when considering the whole code, - -10 -00:00:25,200 --> 00:00:27,860 -and instead your change is affecting the behavior of some of the - -11 -00:00:27,860 --> 00:00:30,980 -other parts of the code. So, it's introducing a regression that will cause - -12 -00:00:30,980 --> 00:00:32,670 -some other functionality, some other piece - -13 -00:00:32,670 --> 00:00:34,320 -of functionality some other feature, to - -14 -00:00:34,320 --> 00:00:37,190 -work incorrectly. So you always have to be careful, and as we saw - -15 -00:00:37,190 --> 00:00:39,750 -at the beginning one way to avoid that is to run tests. - -16 -00:00:39,750 --> 00:00:43,080 -Every time you make a refactoring every time you change your code and - -17 -00:00:43,080 --> 00:00:46,280 -refactor your code. So is to get the least some confidence in - -18 -00:00:46,280 --> 00:00:47,540 -the fact that your refactoring is - -19 -00:00:47,540 --> 00:00:50,290 -indeed behavior preserving. Also consider the refactoring - -20 -00:00:50,290 --> 00:00:54,680 -should not. Be abused. Refactoring should be performed when it's needed. It's - -21 -00:00:54,680 --> 00:00:57,570 -useful to improve the design of your code when you see problems - -22 -00:00:57,570 --> 00:00:59,680 -with the design of the code. Shouldn't just be applied for the - -23 -00:00:59,680 --> 00:01:02,720 -final code because you can apply, for example, easily within a tool. - -24 -00:01:02,720 --> 00:01:06,030 -So be careful not over doing it when you refactor. And for - -25 -00:01:06,030 --> 00:01:08,310 -the same reason that we mentioned at the beginning, you should be - -26 -00:01:08,310 --> 00:01:10,600 -particularly careful when you're using refactoring - -27 -00:01:10,600 --> 00:01:12,290 -for systems that are in production. - -28 -00:01:12,290 --> 00:01:15,260 -Because if you introduce a problem, before the system goes in production, - -29 -00:01:15,260 --> 00:01:16,750 -then you might be able to catch it earlier, - -30 -00:01:16,750 --> 00:01:19,780 -with testing. Or before it's released. But, if you introduce - -31 -00:01:19,780 --> 00:01:21,750 -a problem for a system in production, then you have - -32 -00:01:21,750 --> 00:01:24,440 -to issue a new version of the code. You'll be - -33 -00:01:24,440 --> 00:01:26,860 -affecting, you might be affecting some users, because the code - -34 -00:01:26,860 --> 00:01:29,050 -fails on their machine. So, you have to be twice - -35 -00:01:29,050 --> 00:01:31,190 -as careful, when you are doing refactoring, when you're changing - -36 -00:01:31,190 --> 00:01:33,010 -your code for a system that is already in production. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/19 - Cost of Refactoring - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/19 - Cost of Refactoring - lang_en_vs4.srt deleted file mode 100644 index e09868d..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/19 - Cost of Refactoring - lang_en_vs4.srt +++ /dev/null @@ -1,127 +0,0 @@ -1 -00:00:00,080 --> 00:00:03,800 -Let's also talk about the cost of refactoring. Refactoring might be - -2 -00:00:03,800 --> 00:00:06,750 -free or almost free if you're using a tool to do refactoring - -3 -00:00:06,750 --> 00:00:08,570 -as we did in our demo. But that's not always the - -4 -00:00:08,570 --> 00:00:12,530 -case. In many cases, refactoring involves quite a bit of manual work - -5 -00:00:12,530 --> 00:00:16,309 -if you're doing some manual refactoring. And how much that costs - -6 -00:00:16,309 --> 00:00:19,460 -depends on how well the operations on the source code are supported. - -7 -00:00:19,460 --> 00:00:22,379 -You might have partial support from an ID. You might have complete - -8 -00:00:22,379 --> 00:00:25,017 -support, in which case it's greater. Or you might have no support, - -9 -00:00:25,017 --> 00:00:26,879 -in which case you have to be very careful about - -10 -00:00:26,879 --> 00:00:28,888 -how you change your code and how you check that you - -11 -00:00:28,888 --> 00:00:32,030 -didn't change the behavior of the code. There's also an additional - -12 -00:00:32,030 --> 00:00:34,460 -cost associated with refactoring. Remember - -13 -00:00:34,460 --> 00:00:36,990 -that refactoring relies heavily on testing - -14 -00:00:36,990 --> 00:00:39,808 -after each small step of refactoring. So you might have - -15 -00:00:39,808 --> 00:00:43,451 -to develop test cases, specifically to check your refactoring. And even - -16 -00:00:43,451 --> 00:00:47,163 -if you have an existing test because, for example, you're working - -17 -00:00:47,163 --> 00:00:50,235 -some agile context and therefore you develop a lot of UNIX - -18 -00:00:50,235 --> 00:00:53,550 -test cases before writing your code. And therefore you have a good - -19 -00:00:53,550 --> 00:00:56,635 -regression test with it you can use every time you modify your code. - -20 -00:00:56,635 --> 00:00:59,550 -Nevertheless, when you refactor and you change your code, you might need - -21 -00:00:59,550 --> 00:01:03,255 -to update your test so it's not only the development of the test - -22 -00:01:03,255 --> 00:01:05,379 -cases but also it's maintaining the test cases. And if you have - -23 -00:01:05,379 --> 00:01:07,970 -a lot of test cases, you have to maintain more test cases. So - -24 -00:01:07,970 --> 00:01:12,460 -that's a cost that is not directly visible but can affect quite - -25 -00:01:12,460 --> 00:01:15,800 -a bit the overall cost of refactoring and the overall cost of system - -26 -00:01:15,800 --> 00:01:18,342 -development therefore. And finally, you should not - -27 -00:01:18,342 --> 00:01:21,191 -under estimate the cost of documentation maintenance. - -28 -00:01:21,191 --> 00:01:24,241 -Applying refactoring may involve changes in interfaces, - -29 -00:01:24,241 --> 00:01:26,528 -names, for example, names of classes. And - -30 -00:01:26,528 --> 00:01:29,384 -when you make this kind of changes, you might need to update the documentation, - -31 -00:01:29,384 --> 00:01:30,890 -and that's also cost. It's something that - -32 -00:01:30,890 --> 00:01:32,900 -takes effort and therefore should be considered. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/2 - Introduction - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/2 - Introduction - lang_en_vs4.srt deleted file mode 100644 index a50a2e5..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/2 - Introduction - lang_en_vs4.srt +++ /dev/null @@ -1,127 +0,0 @@ -1 -00:00:00,090 --> 00:00:02,790 -Let me start this lesson by discussing what is refactoring. - -2 -00:00:02,790 --> 00:00:06,590 -Refactoring is the process of applying transformation or refactoring to a - -3 -00:00:06,590 --> 00:00:09,320 -program. So as to obtain a refactor program. With an - -4 -00:00:09,320 --> 00:00:12,850 -improved design but with same functionality as the original program. So - -5 -00:00:12,850 --> 00:00:15,520 -key aspect of refactoring is the fact that refactoring should - -6 -00:00:15,520 --> 00:00:18,150 -be somatic to perserving So what is the main goal of - -7 -00:00:18,150 --> 00:00:22,030 -refactoring? The goal is to keep the program readable, understandable, and - -8 -00:00:22,030 --> 00:00:25,260 -maintainable as we evolve it. And to do this by eliminating - -9 -00:00:25,260 --> 00:00:28,530 -small problems soon, so that you can avoid big trouble later. And - -10 -00:00:28,530 --> 00:00:31,750 -I want to stress once more a key feature of refactoring, which - -11 -00:00:31,750 --> 00:00:34,790 -is the fact that it is behavior per serving. But how can - -12 -00:00:34,790 --> 00:00:38,130 -we ensure that the refactoring is behavior per serving? In other words, - -13 -00:00:38,130 --> 00:00:40,980 -how can we ensure that the program does the same thing before - -14 -00:00:40,980 --> 00:00:43,560 -and after applying a refactoring. So what we would like to do - -15 -00:00:43,560 --> 00:00:47,160 -is to have some guarantee that, that happens. And unfortunately in general, - -16 -00:00:47,160 --> 00:00:50,360 -there are no guarantees. But something we can do is to test - -17 -00:00:50,360 --> 00:00:53,690 -the code. For example, we can write tests that exercise the - -18 -00:00:53,690 --> 00:00:56,390 -parts of the program affected by the refactoring, and if we're in - -19 -00:00:56,390 --> 00:00:59,430 -a [INAUDIBLE] context, we might already have plenty of test cases - -20 -00:00:59,430 --> 00:01:01,914 -that exercise that part of the code. So we might just have - -21 -00:01:01,914 --> 00:01:04,780 -to rerun the test cases after the refactoring. And in fact, - -22 -00:01:04,780 --> 00:01:07,930 -that's a very advantageous situation, and that's a very good use of - -23 -00:01:07,930 --> 00:01:10,970 -existing test cases. And I want to make sure that you remember, - -24 -00:01:10,970 --> 00:01:15,500 -and that you beware that tests provide no guarantees. Testing can only - -25 -00:01:15,500 --> 00:01:18,990 -show the presence of defects, but cannot demonstrate their absence. - -26 -00:01:18,990 --> 00:01:21,090 -So we can use testing to get confidence in our - -27 -00:01:21,090 --> 00:01:23,990 -refactorings, but we can't really guarantee that the refactorings are - -28 -00:01:23,990 --> 00:01:26,820 -behavior preserving. I'd also like to point out that for some - -29 -00:01:26,820 --> 00:01:30,100 -simple refactoring, we can use a static analysis to actually - -30 -00:01:30,100 --> 00:01:33,160 -provide these guarantees. And in fact we will see examples of - -31 -00:01:33,160 --> 00:01:37,050 -such refactorings that are incorporated into IDs and that leverage - -32 -00:01:37,050 --> 00:01:40,070 -these kinds of analysis to perform refactoring in a safe way. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/20 - When Not To Refactor - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/20 - When Not To Refactor - lang_en_vs4.srt deleted file mode 100644 index 53938de..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/20 - When Not To Refactor - lang_en_vs4.srt +++ /dev/null @@ -1,103 +0,0 @@ -1 -00:00:00,088 --> 00:00:02,860 -Now I want to conclude this discussion on refactoring by telling you - -2 -00:00:02,860 --> 00:00:07,190 -when you should not refactor. One first clear case is when - -3 -00:00:07,190 --> 00:00:10,410 -your code is broken. I want to make it very clear, refactoring - -4 -00:00:10,410 --> 00:00:13,450 -is not a way to fix your code in terms of its - -5 -00:00:13,450 --> 00:00:16,250 -functionality. It's a way to improve the design of your code. - -6 -00:00:16,250 --> 00:00:19,040 -So if your code does not compile or does not run - -7 -00:00:19,040 --> 00:00:21,780 -in a stable way, it's probably better to throw it away - -8 -00:00:21,780 --> 00:00:25,250 -and rewrite it rather then trying to refactor it. By definition refactoring - -9 -00:00:25,250 --> 00:00:26,780 -should maintain the functionality of the - -10 -00:00:26,780 --> 00:00:28,360 -system. It should be behavior preserving. - -11 -00:00:28,360 --> 00:00:31,100 -So if the code was broken before, it, it's probably going to be broken - -12 -00:00:31,100 --> 00:00:33,950 -afterwards as well. You may also want to avoid refactoring when a - -13 -00:00:33,950 --> 00:00:37,370 -deadline is close. Well, first of all, because refactoring might take a long - -14 -00:00:37,370 --> 00:00:41,360 -time and therefore might introduce risks of being late for the deadline. - -15 -00:00:41,360 --> 00:00:44,555 -And also, because of what we said before about introducing problems, you don't - -16 -00:00:44,555 --> 00:00:47,780 -want to introduce problems that might take you time to fix right before a - -17 -00:00:47,780 --> 00:00:50,660 -deadline. So if the deadline is too close, you might want to avoid - -18 -00:00:50,660 --> 00:00:54,310 -refactoring the code at that point. And finally, do not refactor if there - -19 -00:00:54,310 --> 00:00:58,430 -is no reason to. As we said before, you should refactor on demand. You - -20 -00:00:58,430 --> 00:01:00,960 -see a problem with the design of your code, with the structure of your - -21 -00:01:00,960 --> 00:01:03,790 -code, it's okay to refactor. If the code is fine, there is no reason - -22 -00:01:03,790 --> 00:01:06,470 -to refactor. I know that refactoring is fine, but you don't want to do - -23 -00:01:06,470 --> 00:01:09,280 -it all the time. The next thing I want to discuss, after discussing when - -24 -00:01:09,280 --> 00:01:12,970 -not to refactor, is when to refactor without an indication that will tell us - -25 -00:01:12,970 --> 00:01:15,820 -that it's time to refactor the code. And that leads us to the discussion - -26 -00:01:15,820 --> 00:01:17,280 -of a very interesting concept. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/21 - Bad Smells - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/21 - Bad Smells - lang_en_vs4.srt deleted file mode 100644 index 240d37b..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/21 - Bad Smells - lang_en_vs4.srt +++ /dev/null @@ -1,99 +0,0 @@ -1 -00:00:00,070 --> 00:00:03,450 -The concept of bad smells. What are bad smells? Well, we - -2 -00:00:03,450 --> 00:00:06,700 -mentioned earlier that refactoring is typically applied when there is something - -3 -00:00:06,700 --> 00:00:09,130 -that does not look right, does not feel right in the - -4 -00:00:09,130 --> 00:00:12,260 -code. And that's exactly what bad smells are. Bad smells, or - -5 -00:00:12,260 --> 00:00:15,320 -code smells if you wish, are symptoms in the code of - -6 -00:00:15,320 --> 00:00:18,868 -a program that might indicate deeper problems. So there might be - -7 -00:00:18,868 --> 00:00:21,775 -parts of my system, classes in my systems, that just don't - -8 -00:00:21,775 --> 00:00:25,309 -smell right, and it feels like there's, there might be something wrong - -9 -00:00:25,309 --> 00:00:29,010 -with them. And if you are an experienced developer just like Brad, - -10 -00:00:29,010 --> 00:00:31,320 -you'll be able to figure out there is something wrong with the - -11 -00:00:31,320 --> 00:00:33,950 -classes. You'll be able to smell that there's something wrong and you'll - -12 -00:00:33,950 --> 00:00:36,880 -do something about it. And I want to mention one more, just to make - -13 -00:00:36,880 --> 00:00:39,270 -sure that we're all on the same page here. That these bad - -14 -00:00:39,270 --> 00:00:43,070 -smells are usually not bugs and don't prevent the program from functioning. They - -15 -00:00:43,070 --> 00:00:46,190 -however indicate weaknesses in the design of the system that might cause - -16 -00:00:46,190 --> 00:00:48,480 -problems during maintenance. In other words, - -17 -00:00:48,480 --> 00:00:50,440 -they might make the code less maintainable, - -18 -00:00:50,440 --> 00:00:53,650 -harder to understand, and so on. Just like refactorings, - -19 -00:00:53,650 --> 00:00:56,610 -there's also many possible different bad smells. So what - -20 -00:00:56,610 --> 00:00:59,160 -I'm providing here is just a possible list of - -21 -00:00:59,160 --> 00:01:02,190 -some very common bad smells. And you can find plenty - -22 -00:01:02,190 --> 00:01:04,349 -of information on this online. So what I want - -23 -00:01:04,349 --> 00:01:06,910 -to do next is just to cover before finishing the - -24 -00:01:06,910 --> 00:01:08,700 -lesson a few of those to show you some - -25 -00:01:08,700 --> 00:01:11,140 -examples of smells and what you can do about them. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/22 - Bad Smell Examples - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/22 - Bad Smell Examples - lang_en_vs4.srt deleted file mode 100644 index b26a698..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/22 - Bad Smell Examples - lang_en_vs4.srt +++ /dev/null @@ -1,263 +0,0 @@ -1 -00:00:00,100 --> 00:00:03,080 -The first example I want to mention is this called duplicated - -2 -00:00:03,080 --> 00:00:06,950 -code. So what happens here what the symptom is, is that you - -3 -00:00:06,950 --> 00:00:10,400 -have the same piece of code. The same fragment of code or - -4 -00:00:10,400 --> 00:00:14,570 -code structure replicated in more than one place. And that's pretty common - -5 -00:00:14,570 --> 00:00:16,880 -when we do for example copy and paste programming. Is something - -6 -00:00:16,880 --> 00:00:19,730 -that we mention at the beginning of the lessons. So for example - -7 -00:00:19,730 --> 00:00:22,780 -we are just instead reimplementing a piece of functionality we know we - -8 -00:00:22,780 --> 00:00:25,510 -already have. We simply copy from a different part of the code. - -9 -00:00:25,510 --> 00:00:27,760 -So what do you do if you have duplicated code? This can - -10 -00:00:27,760 --> 00:00:30,100 -be a problem over time because we might end up with a lot - -11 -00:00:30,100 --> 00:00:34,480 -of duplication in your system. You can use the extract method. Refactoring that - -12 -00:00:34,480 --> 00:00:37,610 -we just saw, and basically create a method that has exactly the same - -13 -00:00:37,610 --> 00:00:40,700 -function as this fragment of code and then replace the fragment of code - -14 -00:00:40,700 --> 00:00:43,030 -with an invocation to run and you will do it in all the - -15 -00:00:43,030 --> 00:00:47,520 -places where the code is duplicated. That simply finds the code and favors - -16 -00:00:47,520 --> 00:00:48,660 -reuse, because there can be more - -17 -00:00:48,660 --> 00:00:51,050 -places that benefit from that additional method. - -18 -00:00:51,050 --> 00:00:54,960 -Especially if it implements some popular piece of functionality. Another example - -19 -00:00:54,960 --> 00:00:57,930 -of best mal a typical one is the long method. So you - -20 -00:00:57,930 --> 00:01:00,530 -have a very long method with a lot of statements. And we - -21 -00:01:00,530 --> 00:01:03,570 -know that the longer procedure, the more difficult it is to understand - -22 -00:01:03,570 --> 00:01:05,650 -it and maintain it. So what I'm going to do in this - -23 -00:01:05,650 --> 00:01:08,690 -case is to factor in such as an extract method or a - -24 -00:01:08,690 --> 00:01:12,900 -decompose conditional to make the code simpler, shorten it. And extract some - -25 -00:01:12,900 --> 00:01:16,450 -of the functionality into other methods. So basically break down the method - -26 -00:01:16,450 --> 00:01:20,180 -in smaller methods that are more cohesive. Another typical example - -27 -00:01:20,180 --> 00:01:22,380 -of best mail which is something that can happen very - -28 -00:01:22,380 --> 00:01:25,720 -commonly during maintenance, is that you keep adding functionality to - -29 -00:01:25,720 --> 00:01:28,470 -a class and you end up with a large class. So - -30 -00:01:28,470 --> 00:01:32,410 -class is clearly to big. It contains too many fields - -31 -00:01:32,410 --> 00:01:35,620 -too many methods, and is just too complex to understand. This - -32 -00:01:35,620 --> 00:01:37,990 -case the obvious solution is to use the extract class - -33 -00:01:37,990 --> 00:01:42,230 -or subclass and basically break down the class in multiple classes. - -34 -00:01:42,230 --> 00:01:45,390 -Each one with a more cohesive piece of functionality. So, the - -35 -00:01:45,390 --> 00:01:46,930 -classes are more cohesive, are more - -36 -00:01:46,930 --> 00:01:48,360 -understandable, and the overall structure The - -37 -00:01:48,360 --> 00:01:52,440 -structure of the system is improved. Shotgun surgery is an interesting smell - -38 -00:01:52,440 --> 00:01:55,980 -and the case here is we are in a situation and you, - -39 -00:01:55,980 --> 00:01:58,270 -probably will happen to you, it definitely happened to me, in - -40 -00:01:58,270 --> 00:02:01,110 -which every time you make some kind of change to the system - -41 -00:02:01,110 --> 00:02:03,850 -you have to make many little changes. All over the place to - -42 -00:02:03,850 --> 00:02:07,280 -many different classes. And this can be a symptom of the fact - -43 -00:02:07,280 --> 00:02:11,080 -that the functionality is spread among these different classes. So - -44 -00:02:11,080 --> 00:02:13,610 -there's too much coupling between the classes and too little - -45 -00:02:13,610 --> 00:02:16,540 -cohesion within the classes. Also in this case you can - -46 -00:02:16,540 --> 00:02:19,540 -use refactoring, for example by using the move method or move - -47 -00:02:19,540 --> 00:02:22,650 -field or inline class to bring the pieces of related - -48 -00:02:22,650 --> 00:02:26,470 -functionality together. So that your resulting classes are more cohesive, you - -49 -00:02:26,470 --> 00:02:29,220 -reduce the dependencies between the different classes, and you address - -50 -00:02:29,220 --> 00:02:32,305 -this problem. Because at this point, each class is much more - -51 -00:02:32,305 --> 00:02:34,020 -self-contained and therefore it can be - -52 -00:02:34,020 --> 00:02:36,100 -modified by itself without having to affect - -53 -00:02:36,100 --> 00:02:38,560 -the rest of the system. The last smell I want to mention is - -54 -00:02:38,560 --> 00:02:42,040 -one I really like, is the feature envy, and it refers to a - -55 -00:02:42,040 --> 00:02:45,340 -method that seems more interested In a class other than the one it - -56 -00:02:45,340 --> 00:02:48,370 -belongs to. So for example this method is using a lot of public - -57 -00:02:48,370 --> 00:02:51,030 -fields of another class, is calling a lot of methods of the other - -58 -00:02:51,030 --> 00:02:53,830 -class. And so in this case the solution is really clear. What you - -59 -00:02:53,830 --> 00:02:57,420 -want to do it to perform the extract method refactoring and then the move - -60 -00:02:57,420 --> 00:02:59,680 -method refactoring so as to take the jealous - -61 -00:02:59,680 --> 00:03:01,210 -method out of the class where it doesn't - -62 -00:03:01,210 --> 00:03:04,770 -belong and get it home. To the class where it really belongs and once more the - -63 -00:03:04,770 --> 00:03:06,790 -effect of this is that you decrease the - -64 -00:03:06,790 --> 00:03:09,990 -coupling between the two classes and therefore you - -65 -00:03:09,990 --> 00:03:11,910 -have a better system and also you eliminate - -66 -00:03:11,910 --> 00:03:13,150 -the envy. Which is always a good thing. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/23 - Bad Smell Quiz - lang_en_vs3.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/23 - Bad Smell Quiz - lang_en_vs3.srt deleted file mode 100644 index 971d639..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/23 - Bad Smell Quiz - lang_en_vs3.srt +++ /dev/null @@ -1,31 +0,0 @@ -1 -00:00:00,100 --> 00:00:01,620 -So now, I would like for you to tell me - -2 -00:00:01,620 --> 00:00:04,810 -which of the following can be considered bad smells in - -3 -00:00:04,810 --> 00:00:07,320 -the context of refactoring. The fact that the program takes - -4 -00:00:07,320 --> 00:00:10,070 -too long to execute? The fact that method M in class - -5 -00:00:10,070 --> 00:00:12,460 -C is very long? Or the, the fact that Class - -6 -00:00:12,460 --> 00:00:16,120 -Cat and Dog are subclasses of class Animal? Or finally the - -7 -00:00:16,120 --> 00:00:18,960 -fact that every time we modify method M1 we also - -8 -00:00:18,960 --> 00:00:22,120 -need to modify method M2? So please mark all that apply. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/24 - Bad Smell Quiz Solution - lang_en_vs3.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/24 - Bad Smell Quiz Solution - lang_en_vs3.srt deleted file mode 100644 index 2773116..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/24 - Bad Smell Quiz Solution - lang_en_vs3.srt +++ /dev/null @@ -1,75 +0,0 @@ -1 -00:00:00,110 --> 00:00:03,090 -So let's look at this one by one. The fact the program takes - -2 -00:00:03,090 --> 00:00:06,620 -too long to execute is not really a bad smell. It probably indicates - -3 -00:00:06,620 --> 00:00:08,800 -some problem with the code and the fact that we might need to - -4 -00:00:08,800 --> 00:00:11,420 -modify the code to make it more efficient, but it's not something that - -5 -00:00:11,420 --> 00:00:14,030 -we will normally classify it as a bad smell, so we're not going to - -6 -00:00:14,030 --> 00:00:17,850 -mark it. The second one, conversely, is definitely a bad smell. The fact - -7 -00:00:17,850 --> 00:00:21,700 -that the method is too long is a typical example of bad smell - -8 -00:00:21,700 --> 00:00:25,000 -and one in which we might want to apply some refactoring, for example, - -9 -00:00:25,000 --> 00:00:26,450 -the extract method or the - -10 -00:00:26,450 --> 00:00:29,240 -decomposed conditional refactorings. There's definitely - -11 -00:00:29,240 --> 00:00:32,159 -nothing wrong with the fact that the classes cat and dog - -12 -00:00:32,159 --> 00:00:35,600 -are subclasses of class animal. Actually, that sounds pretty appropriate, so - -13 -00:00:35,600 --> 00:00:38,270 -this is not a problem and definitely not a bad smell. - -14 -00:00:38,270 --> 00:00:40,990 -Whereas the fact that every time we modify method M1, - -15 -00:00:40,990 --> 00:00:44,210 -we also need to modify method some other method M2 as - -16 -00:00:44,210 --> 00:00:46,690 -a typical example of bad smell. So this can actually be - -17 -00:00:46,690 --> 00:00:50,590 -considered a specific example of what we just called "shotgun surgery." - -18 -00:00:50,590 --> 00:00:52,500 -So it is a case in which we might want to - -19 -00:00:52,500 --> 00:00:55,750 -use, for instance, the move method refactoring to fix the issue. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/3 - Introduction - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/3 - Introduction - lang_en_vs4.srt deleted file mode 100644 index 7631180..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/3 - Introduction - lang_en_vs4.srt +++ /dev/null @@ -1,27 +0,0 @@ -1 -00:00:00,120 --> 00:00:04,280 -So let's have a small quiz and see whether you can remember why can testing - -2 -00:00:04,280 --> 00:00:06,250 -guarantee that that a refactoring is behavior is - -3 -00:00:06,250 --> 00:00:08,590 -preserving. So why testing can only show the - -4 -00:00:08,590 --> 00:00:11,080 -absence of defects and not their presence? - -5 -00:00:11,080 --> 00:00:12,960 -Is that because testing and refactoring are different - -6 -00:00:12,960 --> 00:00:15,980 -activities? Because testing is inherently incomplete? Or, just - -7 -00:00:15,980 --> 00:00:19,560 -because testers are often inexperienced? Make your choice. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/4 - Introduction Solution - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/4 - Introduction Solution - lang_en_vs4.srt deleted file mode 100644 index 7888f8d..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/4 - Introduction Solution - lang_en_vs4.srt +++ /dev/null @@ -1,39 +0,0 @@ -1 -00:00:00,220 --> 00:00:03,180 -And the reason for this is because testing is inherently - -2 -00:00:03,180 --> 00:00:06,080 -incomplete. So let me re-size this a little bit, so that - -3 -00:00:06,080 --> 00:00:08,340 -I can make room for an illustration. And what I'm - -4 -00:00:08,340 --> 00:00:11,170 -going to show you here is just a reminder, that when we - -5 -00:00:11,170 --> 00:00:15,380 -test, we have a huge virtually infinite input domain, and - -6 -00:00:15,380 --> 00:00:17,956 -we have to derive from this input domain a few test - -7 -00:00:17,956 --> 00:00:21,330 -cases. By picking specific inputs in the domain, and of - -8 -00:00:21,330 --> 00:00:25,260 -course, corresponding outputs. And so what happens normally is that these - -9 -00:00:25,260 --> 00:00:28,280 -test cases represent the teeny tiny fraction of - -10 -00:00:28,280 --> 00:00:30,920 -the domain, and therefore testing is always incomplete. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/5 - Reasons to Refactor - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/5 - Reasons to Refactor - lang_en_vs4.srt deleted file mode 100644 index 1da50e6..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/5 - Reasons to Refactor - lang_en_vs4.srt +++ /dev/null @@ -1,131 +0,0 @@ -1 -00:00:00,230 --> 00:00:02,000 -We saw at the beginning of the lesson, what are the - -2 -00:00:02,000 --> 00:00:05,490 -goals of refactoring? Or what are the reasons ,why we need to - -3 -00:00:05,490 --> 00:00:09,130 -refactor in the first place? The first reason is that requirements - -4 -00:00:09,130 --> 00:00:12,370 -change, and when the requirements change, we often need to change our - -5 -00:00:12,370 --> 00:00:16,356 -design accordingly. In other cases if any of the requirements unchange, - -6 -00:00:16,356 --> 00:00:19,690 -we might need to improve our design. And this happens for many - -7 -00:00:19,690 --> 00:00:22,300 -reasons. For example, we need to add a new feature, we - -8 -00:00:22,300 --> 00:00:25,330 -want to make the code more maintainable, and also in general programmers - -9 -00:00:25,330 --> 00:00:28,110 -don't come up with the best design the first time. So they might - -10 -00:00:28,110 --> 00:00:31,130 -need to adapt it after the fact. And the final reason I want to - -11 -00:00:31,130 --> 00:00:33,040 -mention is sloppiness, and to some - -12 -00:00:33,040 --> 00:00:35,700 -extent laziness, of programmers. And a typical - -13 -00:00:35,700 --> 00:00:38,520 -example of this is something that we all have done, which is copy - -14 -00:00:38,520 --> 00:00:41,890 -and paste programming. So instead of rewriting a new piece of code, because - -15 -00:00:41,890 --> 00:00:44,620 -we know that there is some code in some other parts for the - -16 -00:00:44,620 --> 00:00:47,900 -program that does a similar thing, we'll just copy the code over. And - -17 -00:00:47,900 --> 00:00:51,080 -before we know, we end up with tons of copies of the same functionality. - -18 -00:00:51,080 --> 00:00:54,150 -And when that happens, a good way of consolidating that code and - -19 -00:00:54,150 --> 00:00:57,580 -extracting that functionality is to use refactoring, for example, by creating a - -20 -00:00:57,580 --> 00:01:01,080 -method or a class that provides the functionality. And we'll see specific - -21 -00:01:01,080 --> 00:01:03,830 -examples of that. A question I would like to ask at this - -22 -00:01:03,830 --> 00:01:07,330 -point of the class is whether you have used refactoring before? So - -23 -00:01:07,330 --> 00:01:09,690 -I want you to take a second and think about it. And - -24 -00:01:09,690 --> 00:01:12,590 -no matter what you're history is, if you ever coded I bet - -25 -00:01:12,590 --> 00:01:16,180 -you any money that the answer is yes, you have done refactoring. - -26 -00:01:16,180 --> 00:01:17,300 -What do I mean? I'm going to give you an - -27 -00:01:17,300 --> 00:01:19,610 -example. I'm sure you renamed the class or a - -28 -00:01:19,610 --> 00:01:22,190 -method or change the name of some variables in - -29 -00:01:22,190 --> 00:01:25,490 -the code before. That's refactoring. Even something as simple as - -30 -00:01:25,490 --> 00:01:28,030 -renaming a class is refactoring, because, for example, it - -31 -00:01:28,030 --> 00:01:30,230 -might help you making your code more understandable. And of - -32 -00:01:30,230 --> 00:01:32,520 -course I'll admit that in this case, this is - -33 -00:01:32,520 --> 00:01:35,690 -a trivial refactoring, and there are much more interesting ones. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/6 - History of Refactoring - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/6 - History of Refactoring - lang_en_vs4.srt deleted file mode 100644 index 3405b65..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/6 - History of Refactoring - lang_en_vs4.srt +++ /dev/null @@ -1,171 +0,0 @@ -1 -00:00:00,110 --> 00:00:02,340 -So if you follow my class so far, you know that - -2 -00:00:02,340 --> 00:00:04,570 -I like to give a little bit of history when I talk - -3 -00:00:04,570 --> 00:00:06,900 -about a specific topic. So I'm going to do the same also - -4 -00:00:06,900 --> 00:00:09,900 -in this case for refactoring. I'm going to start by mentioning, the fact - -5 -00:00:09,900 --> 00:00:13,440 -that refactoring is something that programmers have always done. I gave - -6 -00:00:13,440 --> 00:00:16,300 -you a trivial example just a minute ago of what refactoring is. - -7 -00:00:16,300 --> 00:00:18,080 -So even more complicated refactorings are - -8 -00:00:18,080 --> 00:00:20,880 -something that are commonplace for developers. - -9 -00:00:20,880 --> 00:00:23,110 -Somehow refactoring is especially important in - -10 -00:00:23,110 --> 00:00:25,240 -the context of object-oriented languages and - -11 -00:00:25,240 --> 00:00:28,080 -probably it's because the object-oriented features are well suited to - -12 -00:00:28,080 --> 00:00:31,640 -make designs flexible and reusable. Because of the fact that help - -13 -00:00:31,640 --> 00:00:35,120 -encapsulation, information hiding, and so they make it easier to - -14 -00:00:35,120 --> 00:00:38,330 -modify something without changing the functionality that it provides to the - -15 -00:00:38,330 --> 00:00:40,960 -outside world. However, you should keep in mind that refactoring - -16 -00:00:40,960 --> 00:00:44,330 -is really not specific to object oriented languages, you can also - -17 -00:00:44,330 --> 00:00:47,320 -refactor other languages, it's just more common to see it in - -18 -00:00:47,320 --> 00:00:50,450 -that context. So one of the first examples of a specific - -19 -00:00:50,450 --> 00:00:53,630 -discussion of what the refactorings are is Opdyke's PhD - -20 -00:00:53,630 --> 00:00:57,710 -thesis in 1990. Which discusses refactorings for small talk. - -21 -00:00:57,710 --> 00:00:59,360 -And some of you might be familiar with small - -22 -00:00:59,360 --> 00:01:02,600 -talk, which is a specific objectory language. And in - -23 -00:01:02,600 --> 00:01:06,590 -more recent times, refactoring's becoming increasing popular due to - -24 -00:01:06,590 --> 00:01:10,370 -lightweight development methodoogies, due to agile development, which is - -25 -00:01:10,370 --> 00:01:12,630 -something that we just discussed in this class. For - -26 -00:01:12,630 --> 00:01:15,830 -example, when we talked about extreme programming, we mentioned refactoring - -27 -00:01:15,830 --> 00:01:17,950 -a few times. And the reason why its so popular - -28 -00:01:17,950 --> 00:01:20,690 -is because re-factoring is one of the practices that help. - -29 -00:01:20,690 --> 00:01:24,780 -Making changes less expensive. And therefore adapt to changing requirements - -30 -00:01:24,780 --> 00:01:26,980 -and changing environments more quickly. - -31 -00:01:26,980 --> 00:01:29,140 -And continuing with historical perspective, one - -32 -00:01:29,140 --> 00:01:31,760 -of the milestones in the history of re-factoring [INAUDIBLE] is - -33 -00:01:31,760 --> 00:01:34,660 -a book by Martin Fowler. This is a book entitled - -34 -00:01:34,660 --> 00:01:37,610 -Improving the Design of Existing [INAUDIBLE]. And it contains a - -35 -00:01:37,610 --> 00:01:41,320 -catalog of refactorings, a list of bad smells, in code, and - -36 -00:01:41,320 --> 00:01:43,450 -we're going to see what that mean exactly. Nothing to - -37 -00:01:43,450 --> 00:01:45,570 -do with other kinds of bad smells. It talks about - -38 -00:01:45,570 --> 00:01:48,900 -guidelines on when to apply refactoring. And finally, which is - -39 -00:01:48,900 --> 00:01:52,540 -very useful, it provides example of code, before and after. - -40 -00:01:52,540 --> 00:01:54,660 -Applying the refactoring and we're going to use more of the - -41 -00:01:54,660 --> 00:01:57,190 -same style when discussing refactoring in the rest of this - -42 -00:01:57,190 --> 00:02:01,090 -lesson. More specifically what we're discussing next, are some examples - -43 -00:02:01,090 --> 00:02:05,130 -of refactoring and also some examples of code bad smells. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/7 - Types of Refactorings - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/7 - Types of Refactorings - lang_en_vs4.srt deleted file mode 100644 index b646b14..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/7 - Types of Refactorings - lang_en_vs4.srt +++ /dev/null @@ -1,43 +0,0 @@ -1 -00:00:00,170 --> 00:00:03,630 -There are many refactorings in Fowler's book, and what I'm - -2 -00:00:03,630 --> 00:00:06,480 -showing here is just a partial list. And we're not going to - -3 -00:00:06,480 --> 00:00:08,930 -have time to go through the complete list of refactorings, - -4 -00:00:08,930 --> 00:00:10,830 -so what I'm going to do instead, I'm just going to pick a - -5 -00:00:10,830 --> 00:00:13,870 -few of those, but I'm going to explain in more depth, - -6 -00:00:13,870 --> 00:00:16,600 -and for which I'm going to provide some examples. In particular, we're - -7 -00:00:16,600 --> 00:00:18,000 -going to talk about the collapse - -8 -00:00:18,000 --> 00:00:20,630 -hierarchy refactoring, the consolidate conditional - -9 -00:00:20,630 --> 00:00:23,600 -expressions, the decompose conditionals, extract - -10 -00:00:23,600 --> 00:00:25,418 -method, extract class, and inline class. - -11 -00:00:25,418 --> 00:00:29,420 -And we're going to see each of those individually in the rest of the lesson. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/8 - Collapse Hierarchy - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/8 - Collapse Hierarchy - lang_en_vs4.srt deleted file mode 100644 index 8711182..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/8 - Collapse Hierarchy - lang_en_vs4.srt +++ /dev/null @@ -1,67 +0,0 @@ -1 -00:00:00,110 --> 00:00:03,080 -The first refactoring we're going to see is the collapse hierarchy - -2 -00:00:03,080 --> 00:00:06,340 -refactoring. When a software system undergoes a number of changes, over - -3 -00:00:06,340 --> 00:00:09,730 -time the collapse hierarchy may become, let's say, sub-optimal. There are - -4 -00:00:09,730 --> 00:00:11,300 -several refactorings that address this - -5 -00:00:11,300 --> 00:00:13,200 -issue for example, refactorings that allow - -6 -00:00:13,200 --> 00:00:15,900 -you to move methods and fields up and down the class - -7 -00:00:15,900 --> 00:00:18,360 -hierarchy. So what happens when you apply a number of these - -8 -00:00:18,360 --> 00:00:22,360 -refactorings, is that a subclass might become too similar to its - -9 -00:00:22,360 --> 00:00:25,878 -superclass and might not be adding much value to the system. - -10 -00:00:25,878 --> 00:00:28,010 -In this case, it is a good idea to merge - -11 -00:00:28,010 --> 00:00:31,300 -the classes together. That's exactly what the Collapse Hierarchy refactoring - -12 -00:00:31,300 --> 00:00:34,600 -does. Imagine, for instance, that we have two classes: employee - -13 -00:00:34,600 --> 00:00:38,210 -and salesman. And that salesman is just so similar to - -14 -00:00:38,210 --> 00:00:40,380 -employee that it does not make sense to keep them - -15 -00:00:40,380 --> 00:00:43,870 -separated. In this case, you could merge the two classes, - -16 -00:00:43,870 --> 00:00:46,730 -so that at the end of the refactoring, only employee - -17 -00:00:46,730 --> 00:00:50,070 -is left. And the resulting structure of the system is improved. diff --git a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/9 - Consolidate Conditional Expression - lang_en_vs4.srt b/usth/ICT2.7/P4L5 Software Refactoring Subtitles/9 - Consolidate Conditional Expression - lang_en_vs4.srt deleted file mode 100644 index be2b3fe..0000000 --- a/usth/ICT2.7/P4L5 Software Refactoring Subtitles/9 - Consolidate Conditional Expression - lang_en_vs4.srt +++ /dev/null @@ -1,131 +0,0 @@ -1 -00:00:00,070 --> 00:00:00,860 -We're now going to talk about - -2 -00:00:00,860 --> 00:00:03,390 -the consolidate conditional expression refactoring. - -3 -00:00:03,390 --> 00:00:05,730 -A common situation in code is that you have a set - -4 -00:00:05,730 --> 00:00:08,530 -of conditionals with the same result. What that means that - -5 -00:00:08,530 --> 00:00:12,090 -sometimes the code contains a series of conditional checks in which - -6 -00:00:12,090 --> 00:00:14,760 -each check is different, yet the resulting action is the - -7 -00:00:14,760 --> 00:00:18,440 -same. In these cases, the code could be improved by combining - -8 -00:00:18,440 --> 00:00:22,100 -the conditionals using, for example, and, and or, as connectors. So - -9 -00:00:22,100 --> 00:00:25,390 -as to have a single conditional check, with a single result. - -10 -00:00:25,390 --> 00:00:28,500 -At that point you can also extract those conditional into a - -11 -00:00:28,500 --> 00:00:32,310 -method. And replace the conditional with a call, to debt matter consolidating - -12 -00:00:32,310 --> 00:00:35,110 -the conditional code in this way can make the checks clearer - -13 -00:00:35,110 --> 00:00:38,170 -by showing that you're really making a single check rather than multiple - -14 -00:00:38,170 --> 00:00:41,150 -checks, and extracted that condition and having that matter instead of - -15 -00:00:41,150 --> 00:00:44,550 -a condition can clarify your code by explaining why you're doing a - -16 -00:00:44,550 --> 00:00:47,350 -given check, rather than how you're doing it. You can see an - -17 -00:00:47,350 --> 00:00:52,020 -example of that situation in this code, which is the disabilityAmount method. - -18 -00:00:52,020 --> 00:00:54,580 -As the name of the method says, the purpose of this code - -19 -00:00:54,580 --> 00:00:58,300 -is to compute the disability amount for a given, for example, employee. - -20 -00:00:58,300 --> 00:01:01,250 -And there is a set of initial checks in the methods whose - -21 -00:01:01,250 --> 00:01:05,090 -goal is to decide whether there's this disabilityAmount should be instead zero. - -22 -00:01:05,090 --> 00:01:07,750 -And as you can see, there's multiple conditions. For example, there's a - -23 -00:01:07,750 --> 00:01:10,630 -check about the seniority level, and about the number of months that - -24 -00:01:10,630 --> 00:01:14,350 -the employee's been disabled. So far, whether the employee is part time - -25 -00:01:14,350 --> 00:01:17,060 -and the outcome of all these check is always the same. If they're - -26 -00:01:17,060 --> 00:01:19,740 -true, if the check is satisfied then there is no disability - -27 -00:01:19,740 --> 00:01:22,564 -amount. So the disabilityAmount is zero. So what I will do - -28 -00:01:22,564 --> 00:01:25,986 -if I apply the consolidate conditional expression to this matter, is - -29 -00:01:25,986 --> 00:01:29,690 -that I will take these three conditionals. I will put them together - -30 -00:01:29,690 --> 00:01:32,772 -by saying basically that if seniority is less than 2 or - -31 -00:01:32,772 --> 00:01:36,524 -monthsDisabled is greater than 12 or isPartTime is true then the - -32 -00:01:36,524 --> 00:01:40,170 -return should be zero. And once I have this combined conditional, - -33 -00:01:40,170 --> 00:01:42,601 -as I see here, I will just extract that into a method. |