WEBVTT 00:00.260 --> 00:05.630 So what you are seeing right now is a syntax for the arrow functions. 00:05.630 --> 00:09.290 And they're also known as short closures. 00:09.800 --> 00:11.360 So this might ring a bell. 00:11.360 --> 00:17.750 We've already talked about closures in PHP and this was anonymous functions. 00:17.750 --> 00:24.830 Functions without a name that are passed as an argument to a function or associated with a variable. 00:24.860 --> 00:31.640 So those arrow functions were introduced in PHP 7.4. 00:31.670 --> 00:39.890 That's just a more concise way if you need to write short single expression functions. 00:39.890 --> 00:42.590 So this is really important. 00:42.620 --> 00:47.540 Arrow functions can only have one single expression. 00:47.540 --> 00:50.960 And there is an implicit return. 00:50.960 --> 00:59.090 What this means is in normal functions or the other functions than the arrow functions, whether that's 00:59.090 --> 01:00.500 a closure or not. 01:00.650 --> 01:06.070 To return something you need to use the return keyword here. 01:06.550 --> 01:07.840 Well, you can do that. 01:07.840 --> 01:14.590 But also whatever this expression evaluates to is returned from such function. 01:14.590 --> 01:21.730 And well, the other things this function, this arrow function is not using the function keyword, 01:21.730 --> 01:23.680 instead it is fn. 01:23.830 --> 01:30.730 Then you have some optional arguments and instead of the curly braces you have this arrow symbol. 01:30.730 --> 01:34.960 So those two characters and a semicolon. 01:34.960 --> 01:42.460 After this single expression which is implicitly returned, let's now jump to the code editor and see 01:42.490 --> 01:44.230 some actual examples. 01:45.250 --> 01:58.000 So let's make an arrow PHP file, and the plan is to see an array of numbers being squared using an 01:58.000 --> 01:59.710 array map function. 01:59.710 --> 02:02.320 And we're going to have two examples. 02:02.320 --> 02:05.170 So traditional anonymous function. 02:05.170 --> 02:10.770 So you can see how much shorter the new arrow function syntax is. 02:12.510 --> 02:14.760 So this is something super simple. 02:14.790 --> 02:16.080 An array of numbers. 02:16.080 --> 02:17.730 We've used that before. 02:18.120 --> 02:20.460 Then a squared variable. 02:20.460 --> 02:27.900 So we're going to use array map which is essentially like doing a foreach and creating a new array. 02:27.900 --> 02:36.420 But instead of using the for each loop we can call this function the array map that accepts an anonymous 02:36.420 --> 02:45.510 function like that from which we just return n times n. 02:48.270 --> 02:53.220 And we also tell it that the input is this numbers array. 02:53.220 --> 02:57.750 The result stored in squared would be a new array. 02:57.750 --> 03:06.720 Let's just dump this array and also the original one so we can see the results. 03:07.290 --> 03:09.810 So we run PHP or PHP. 03:10.110 --> 03:11.760 There are the two arrays. 03:11.910 --> 03:13.650 That's the original one. 03:13.650 --> 03:16.460 And this is the squared one. 03:17.750 --> 03:21.410 So I think that we have probably did this example before. 03:21.410 --> 03:23.990 So there is nothing special to explain here. 03:24.020 --> 03:30.350 Now let me show you the same example, but this time by using arrow functions. 03:30.380 --> 03:34.100 So the first change is function is change to fn. 03:34.130 --> 03:36.590 Then we just get this parameter. 03:37.760 --> 03:39.770 There is no curly braces. 03:39.770 --> 03:48.320 Instead there is this arrow symbol equality sign and more than placed together there is no return keyword 03:48.320 --> 03:52.970 as arrow functions implicitly return the value. 03:53.120 --> 03:55.400 Let's get rid of this curly brace. 03:55.400 --> 03:59.570 And also in this case there is no need for a semicolon. 03:59.600 --> 04:05.870 I can also move this to some separate lines so it's clearly visible. 04:06.350 --> 04:10.760 This is how this new arrow function looks like. 04:10.790 --> 04:20.350 Instead of this much shorter syntax, and very useful for cases like passing a closure to one of the 04:20.350 --> 04:28.480 built in PHP functions for processing arrays and other different functions that you might not know yet. 04:30.370 --> 04:37.300 Finally, let's assign this to squared two and just make sure that it works. 04:39.010 --> 04:44.800 So there is the output same in both race, which means that it works normally. 04:46.330 --> 04:49.930 Now that's not everything about the arrow functions. 04:49.960 --> 04:54.070 Let me introduce a variable that would be global. 04:54.100 --> 04:57.610 Let me call that multiplier. 04:57.670 --> 05:04.660 So instead of squaring the values from this array we're gonna multiply it by the multiplier. 05:04.660 --> 05:08.800 So let's first do it with this traditional closure. 05:10.000 --> 05:11.350 I can do it like this. 05:11.350 --> 05:21.610 Now you probably remember this won't work as this closure can't access a variable from the outside scope 05:21.610 --> 05:26.640 and it just returns zeros everywhere and there should be a warning on the top. 05:27.000 --> 05:35.730 The variable multiplier is undefined, so traditional closures can't access global variables variables 05:35.730 --> 05:37.860 from outside its scope. 05:38.160 --> 05:46.290 To do it, you need to use this use statement and only then use multiplier. 05:46.290 --> 05:49.560 And then you can use this variable. 05:49.560 --> 05:52.950 So you can see that this is getting really complex. 05:53.040 --> 06:01.770 Now that's not the case with arrow functions as arrow functions as the arrow functions just inherit 06:01.770 --> 06:04.980 the variables from the parent scope. 06:04.980 --> 06:09.570 So arrow functions work out of the box with outside variables. 06:09.570 --> 06:12.540 No need to add any use statements. 06:13.020 --> 06:16.410 If I run this script right now, we get the output. 06:16.410 --> 06:23.370 So everything is properly calculated and there are no issues whatsoever. 06:23.400 --> 06:28.680 As I've said, you can just use outside variables with arrow functions.