1 1 00:00:01,280 --> 00:00:02,840 Hi guys and welcome back. 2 2 00:00:02,840 --> 00:00:05,823 Let's look at the at syntax for decorators. 3 3 00:00:06,680 --> 00:00:09,020 Here we've got our code from the last video. 4 4 00:00:09,020 --> 00:00:11,280 We have our make secure function, 5 5 00:00:11,280 --> 00:00:13,060 that defines an inner function, 6 6 00:00:13,060 --> 00:00:15,220 that will be used to replace, 7 7 00:00:15,220 --> 00:00:17,790 the function that we want to make secure. 8 8 00:00:17,790 --> 00:00:19,660 This function checks the access level, 9 9 00:00:19,660 --> 00:00:22,250 and then returns a call to the original one, 10 10 00:00:22,250 --> 00:00:24,453 such as the get admin password function. 11 11 00:00:25,320 --> 00:00:28,540 Now I'll have you know that instead of doing this 12 12 00:00:28,540 --> 00:00:31,510 get admin password equal make secure of get admin password, 13 13 00:00:31,510 --> 00:00:32,680 which can have some problems, 14 14 00:00:32,680 --> 00:00:35,300 for example if you decide to call get admin password 15 15 00:00:35,300 --> 00:00:39,300 before that line runs you can use the at syntax, 16 16 00:00:39,300 --> 00:00:42,060 which does exactly the same thing. 17 17 00:00:42,060 --> 00:00:45,100 That is at make secure, 18 18 00:00:45,100 --> 00:00:48,410 if you put at make secure in front of or on top of 19 19 00:00:48,410 --> 00:00:52,070 a function definition that will prevent the function 20 20 00:00:52,070 --> 00:00:55,150 from being created as is and instead it will create it 21 21 00:00:55,150 --> 00:00:57,910 and pass it through the decorator, in one go. 22 22 00:00:57,910 --> 00:00:59,990 Though you no longer need that here 23 23 00:00:59,990 --> 00:01:02,260 and now you'll see that if we run this code 24 24 00:01:02,260 --> 00:01:05,320 you will get no admin permissions for Jose. 25 25 00:01:05,320 --> 00:01:07,190 Because at the moment I am a guest, 26 26 00:01:07,190 --> 00:01:09,380 but if I change this to an admin, 27 27 00:01:09,380 --> 00:01:11,103 then it will all work out. 28 28 00:01:12,600 --> 00:01:15,520 However there is a small problem with decorators as a whole. 29 29 00:01:15,520 --> 00:01:16,910 Both when you assign them 30 30 00:01:16,910 --> 00:01:19,030 and also when you use the at syntax. 31 31 00:01:19,030 --> 00:01:21,530 Which is that when you replace this function, 32 32 00:01:21,530 --> 00:01:24,022 by this one here, 33 33 00:01:24,022 --> 00:01:27,670 the name of the function changes. 34 34 00:01:27,670 --> 00:01:30,210 The get admin password it still exists 35 35 00:01:30,210 --> 00:01:32,570 as a name inside Python 36 36 00:01:32,570 --> 00:01:35,740 but it is no longer registered as a function internally. 37 37 00:01:35,740 --> 00:01:37,670 Now the secure function is registered 38 38 00:01:37,670 --> 00:01:39,400 as a function internally, 39 39 00:01:39,400 --> 00:01:41,220 and there are some libraries that will 40 40 00:01:41,220 --> 00:01:43,440 actually use that internal name. 41 41 00:01:43,440 --> 00:01:47,750 So, for example if you print get admin password dot name 42 42 00:01:47,750 --> 00:01:48,900 you'll see what I mean. 43 43 00:01:49,750 --> 00:01:53,870 The name of get admin password, is actually secure function. 44 44 00:01:53,870 --> 00:01:56,020 So, that is a bit of a problem, 45 45 00:01:56,020 --> 00:01:57,960 a problem that we have to solve. 46 46 00:01:57,960 --> 00:02:01,240 In addition, if you have any documentation attached 47 47 00:02:01,240 --> 00:02:04,100 to get admin password it will also be lost 48 48 00:02:04,100 --> 00:02:06,060 when you replace it with secure function, 49 49 00:02:06,060 --> 00:02:08,550 because this one doesn't have any documentation. 50 50 00:02:08,550 --> 00:02:10,500 To fix that problem all you have to do 51 51 00:02:10,500 --> 00:02:12,780 is actually use another decorator. 52 52 00:02:12,780 --> 00:02:15,493 So, will go into import functools, 53 53 00:02:16,720 --> 00:02:18,580 which is short for function tools, 54 54 00:02:18,580 --> 00:02:21,240 this is a built in module in Python, 55 55 00:02:21,240 --> 00:02:23,990 and then we're going to decorate our secure function. 56 56 00:02:23,990 --> 00:02:27,510 We're gonna say at functools dot wraps 57 57 00:02:27,510 --> 00:02:29,480 and then we're going to tell secure function 58 58 00:02:29,480 --> 00:02:32,860 that it is a wrapper for func. 59 59 00:02:32,860 --> 00:02:35,160 And therefore what this does is essentially 60 60 00:02:35,160 --> 00:02:37,730 it keeps the name and the documentation 61 61 00:02:37,730 --> 00:02:40,053 of this function if there are any. 62 62 00:02:40,930 --> 00:02:42,270 So the name is always gonna be there 63 63 00:02:42,270 --> 00:02:44,700 if we now run this code you can see 64 64 00:02:44,700 --> 00:02:46,810 that get admin password is what comes out. 65 65 00:02:46,810 --> 00:02:49,600 So that's what the functools wraps is for 66 66 00:02:49,600 --> 00:02:53,060 you need that on pretty much every decorator you write, 67 67 00:02:53,060 --> 00:02:54,910 so do get accustomed to using that. 68 68 00:02:54,910 --> 00:02:56,710 Remember, you wanna put it on top of 69 69 00:02:56,710 --> 00:02:58,700 the inner secure function 70 70 00:02:58,700 --> 00:03:01,643 not on top of this make secure decorator. 71 71 00:03:02,870 --> 00:03:04,960 Some terminology at this point by the way 72 72 00:03:04,960 --> 00:03:08,230 the make secure function is called a decorator 73 73 00:03:08,230 --> 00:03:10,930 because you can use it decorate a function. 74 74 00:03:10,930 --> 00:03:12,770 This here is not a decorator, 75 75 00:03:12,770 --> 00:03:15,570 that's just a function that will replace your other one. 76 76 00:03:17,630 --> 00:03:19,520 All right, that's everything for this video. 77 77 00:03:19,520 --> 00:03:22,160 I wanted to show you the at syntax for decorators 78 78 00:03:22,160 --> 00:03:25,840 and also functools wraps those two are essential 79 79 00:03:25,840 --> 00:03:28,300 when you're working with decorators in Python. 80 80 00:03:28,300 --> 00:03:29,610 Thanks for joining me in this one, 81 81 00:03:29,610 --> 00:03:30,660 hope you've learned something, 82 82 00:03:30,660 --> 00:03:32,410 and I'll see you in the next video.