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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. |