WEBVTT 1 00:00:01.280 --> 00:00:02.840 Hi guys and welcome back. 2 00:00:02.840 --> 00:00:05.823 Let's look at the at syntax for decorators. 3 00:00:06.680 --> 00:00:09.020 Here we've got our code from the last video. 4 00:00:09.020 --> 00:00:11.280 We have our make secure function, 5 00:00:11.280 --> 00:00:13.060 that defines an inner function, 6 00:00:13.060 --> 00:00:15.220 that will be used to replace, 7 00:00:15.220 --> 00:00:17.790 the function that we want to make secure. 8 00:00:17.790 --> 00:00:19.660 This function checks the access level, 9 00:00:19.660 --> 00:00:22.250 and then returns a call to the original one, 10 00:00:22.250 --> 00:00:24.453 such as the get admin password function. 11 00:00:25.320 --> 00:00:28.540 Now I'll have you know that instead of doing this 12 00:00:28.540 --> 00:00:31.510 get admin password equal make secure of get admin password, 13 00:00:31.510 --> 00:00:32.680 which can have some problems, 14 00:00:32.680 --> 00:00:35.300 for example if you decide to call get admin password 15 00:00:35.300 --> 00:00:39.300 before that line runs you can use the at syntax, 16 00:00:39.300 --> 00:00:42.060 which does exactly the same thing. 17 00:00:42.060 --> 00:00:45.100 That is at make secure, 18 00:00:45.100 --> 00:00:48.410 if you put at make secure in front of or on top of 19 00:00:48.410 --> 00:00:52.070 a function definition that will prevent the function 20 00:00:52.070 --> 00:00:55.150 from being created as is and instead it will create it 21 00:00:55.150 --> 00:00:57.910 and pass it through the decorator, in one go. 22 00:00:57.910 --> 00:00:59.990 Though you no longer need that here 23 00:00:59.990 --> 00:01:02.260 and now you'll see that if we run this code 24 00:01:02.260 --> 00:01:05.320 you will get no admin permissions for Jose. 25 00:01:05.320 --> 00:01:07.190 Because at the moment I am a guest, 26 00:01:07.190 --> 00:01:09.380 but if I change this to an admin, 27 00:01:09.380 --> 00:01:11.103 then it will all work out. 28 00:01:12.600 --> 00:01:15.520 However there is a small problem with decorators as a whole. 29 00:01:15.520 --> 00:01:16.910 Both when you assign them 30 00:01:16.910 --> 00:01:19.030 and also when you use the at syntax. 31 00:01:19.030 --> 00:01:21.530 Which is that when you replace this function, 32 00:01:21.530 --> 00:01:24.022 by this one here, 33 00:01:24.022 --> 00:01:27.670 the name of the function changes. 34 00:01:27.670 --> 00:01:30.210 The get admin password it still exists 35 00:01:30.210 --> 00:01:32.570 as a name inside Python 36 00:01:32.570 --> 00:01:35.740 but it is no longer registered as a function internally. 37 00:01:35.740 --> 00:01:37.670 Now the secure function is registered 38 00:01:37.670 --> 00:01:39.400 as a function internally, 39 00:01:39.400 --> 00:01:41.220 and there are some libraries that will 40 00:01:41.220 --> 00:01:43.440 actually use that internal name. 41 00:01:43.440 --> 00:01:47.750 So, for example if you print get admin password dot name 42 00:01:47.750 --> 00:01:48.900 you'll see what I mean. 43 00:01:49.750 --> 00:01:53.870 The name of get admin password, is actually secure function. 44 00:01:53.870 --> 00:01:56.020 So, that is a bit of a problem, 45 00:01:56.020 --> 00:01:57.960 a problem that we have to solve. 46 00:01:57.960 --> 00:02:01.240 In addition, if you have any documentation attached 47 00:02:01.240 --> 00:02:04.100 to get admin password it will also be lost 48 00:02:04.100 --> 00:02:06.060 when you replace it with secure function, 49 00:02:06.060 --> 00:02:08.550 because this one doesn't have any documentation. 50 00:02:08.550 --> 00:02:10.500 To fix that problem all you have to do 51 00:02:10.500 --> 00:02:12.780 is actually use another decorator. 52 00:02:12.780 --> 00:02:15.493 So, will go into import functools, 53 00:02:16.720 --> 00:02:18.580 which is short for function tools, 54 00:02:18.580 --> 00:02:21.240 this is a built in module in Python, 55 00:02:21.240 --> 00:02:23.990 and then we're going to decorate our secure function. 56 00:02:23.990 --> 00:02:27.510 We're gonna say at functools dot wraps 57 00:02:27.510 --> 00:02:29.480 and then we're going to tell secure function 58 00:02:29.480 --> 00:02:32.860 that it is a wrapper for func. 59 00:02:32.860 --> 00:02:35.160 And therefore what this does is essentially 60 00:02:35.160 --> 00:02:37.730 it keeps the name and the documentation 61 00:02:37.730 --> 00:02:40.053 of this function if there are any. 62 00:02:40.930 --> 00:02:42.270 So the name is always gonna be there 63 00:02:42.270 --> 00:02:44.700 if we now run this code you can see 64 00:02:44.700 --> 00:02:46.810 that get admin password is what comes out. 65 00:02:46.810 --> 00:02:49.600 So that's what the functools wraps is for 66 00:02:49.600 --> 00:02:53.060 you need that on pretty much every decorator you write, 67 00:02:53.060 --> 00:02:54.910 so do get accustomed to using that. 68 00:02:54.910 --> 00:02:56.710 Remember, you wanna put it on top of 69 00:02:56.710 --> 00:02:58.700 the inner secure function 70 00:02:58.700 --> 00:03:01.643 not on top of this make secure decorator. 71 00:03:02.870 --> 00:03:04.960 Some terminology at this point by the way 72 00:03:04.960 --> 00:03:08.230 the make secure function is called a decorator 73 00:03:08.230 --> 00:03:10.930 because you can use it decorate a function. 74 00:03:10.930 --> 00:03:12.770 This here is not a decorator, 75 00:03:12.770 --> 00:03:15.570 that's just a function that will replace your other one. 76 00:03:17.630 --> 00:03:19.520 All right, that's everything for this video. 77 00:03:19.520 --> 00:03:22.160 I wanted to show you the at syntax for decorators 78 00:03:22.160 --> 00:03:25.840 and also functools wraps those two are essential 79 00:03:25.840 --> 00:03:28.300 when you're working with decorators in Python. 80 00:03:28.300 --> 00:03:29.610 Thanks for joining me in this one, 81 00:03:29.610 --> 00:03:30.660 hope you've learned something, 82 00:03:30.660 --> 00:03:32.410 and I'll see you in the next video.