1
00:00:00,560 --> 00:00:03,270
Next up is something you may not use
often, but

2
00:00:03,270 --> 00:00:06,270
is a good thing to know, and those are
closures.

3
00:00:06,270 --> 00:00:10,060
Closures are anonymous functions, which
are functions with no name,

4
00:00:10,060 --> 00:00:14,190
that are capable of accessing variables
outside of the function scope.

5
00:00:14,190 --> 00:00:17,540
We'll talk more about the use of closures
as call backs when we

6
00:00:17,540 --> 00:00:19,550
get to the internal functions video.

7
00:00:19,550 --> 00:00:21,530
For now, let's look at how this works.

8
00:00:24,330 --> 00:00:27,860
Okay, to provide an example of a closure,
let's start by opening and

9
00:00:27,860 --> 00:00:30,690
closing a set of PHP tags.

10
00:00:30,690 --> 00:00:33,720
Then inside of those, we're gonna do it a
little bit differently.

11
00:00:33,720 --> 00:00:36,760
Before we had used the function keyword,
right?

12
00:00:36,760 --> 00:00:39,330
And then added a name for our function.

13
00:00:39,330 --> 00:00:44,000
In this case, we're going to use $greet as
a variable, and

14
00:00:44,000 --> 00:00:48,620
then set it equal to function, and then
open and close parentheses.

15
00:00:48,620 --> 00:00:51,310
And then open and close our curly braces,
and

16
00:00:51,310 --> 00:00:55,850
then follow that as a statement, enclosing
it with a semi-colon.

17
00:00:55,850 --> 00:01:01,270
So what this is going to do is whatever we
do inside this function, it's going to set

18
00:01:01,270 --> 00:01:07,780
its output to greet, $greet will contain
whatever function produces.

19
00:01:07,780 --> 00:01:08,760
So let's do this.

20
00:01:08,760 --> 00:01:13,990
We'll add inside the function echo Hello
there and then close that statement.

21
00:01:13,990 --> 00:01:18,800
This way, when we call $greet then we'll
get hello there.

22
00:01:18,800 --> 00:01:22,910
Now let's say we have something outside of
the function scope.

23
00:01:22,910 --> 00:01:26,740
Well anonymous functions are not able to
access things outside of

24
00:01:26,740 --> 00:01:31,400
the function scope unless we utilize the
use keyword.

25
00:01:31,400 --> 00:01:36,490
So what we'll do here is if we have a
variable named $name and that's equal

26
00:01:36,490 --> 00:01:41,380
to friend and we wanna use it in our greet
function, or our greet anonymous function,

27
00:01:41,380 --> 00:01:47,530
then we simply say function use, and then
in parentheses, $name.

28
00:01:47,530 --> 00:01:52,634
This way, inside of our statement, inside
of the function we can say,

29
00:01:52,634 --> 00:01:54,686
echo Hello there, $name.

30
00:01:54,686 --> 00:01:57,049
Notice how I've surrounded it in double
quotes now so

31
00:01:57,049 --> 00:02:00,300
that we can actually output the value of
the string.

32
00:02:00,300 --> 00:02:02,990
So to build out our example in WorkSpaces,

33
00:02:02,990 --> 00:02:06,396
we are going to define our anonymous
function or

34
00:02:06,396 --> 00:02:11,720
our closure with $greet as the name and
then we'll set that equal to a function.

35
00:02:13,110 --> 00:02:15,220
And then open and close our parenthesis.

36
00:02:15,220 --> 00:02:17,000
Open and close our curly braces, but

37
00:02:17,000 --> 00:02:20,660
the big case here is to make sure you end
this in a semicolon.

38
00:02:20,660 --> 00:02:23,580
So a anonymous function is really more
like

39
00:02:23,580 --> 00:02:27,420
a single line function that's being
assigned to a variable.

40
00:02:27,420 --> 00:02:29,490
So we'll make sure we end it in a
semicolon and

41
00:02:29,490 --> 00:02:32,160
then inside we'll actually do an echo
statement.

42
00:02:32,160 --> 00:02:39,390
So we'll say echo and then our echo will
be hello there, okay?

43
00:02:39,390 --> 00:02:40,890
Close it with a semicolon and

44
00:02:40,890 --> 00:02:45,850
then in order to call this, we'll simply
type in $greet and

45
00:02:45,850 --> 00:02:49,990
then open and closed parenthesis, just
like we did in a variable function.

46
00:02:49,990 --> 00:02:52,770
Let's head over to our preview and take a
look.

47
00:02:52,770 --> 00:02:57,120
Okay, so you'll see here we have hello and
in there exclamation point.

48
00:02:57,120 --> 00:02:59,140
So, that's exactly what we're looking for.

49
00:02:59,140 --> 00:03:02,370
Okay, so let's head back over to
WorkSpaces and

50
00:03:02,370 --> 00:03:05,030
build out this example just a little bit
more.

51
00:03:05,030 --> 00:03:06,992
Let's say we wanna greet a name.

52
00:03:06,992 --> 00:03:09,200
All right, so we'll say function and

53
00:03:09,200 --> 00:03:13,530
then we want something outside of the
function scope.

54
00:03:13,530 --> 00:03:18,610
So we'll have something like name, and
then we'll set that equal to Mike.

55
00:03:18,610 --> 00:03:19,390
All right.

56
00:03:19,390 --> 00:03:22,740
So inside of our function we want to
access $name.

57
00:03:22,740 --> 00:03:27,760
Well we can't just pass it through as an
argument and we don't want to use global.

58
00:03:27,760 --> 00:03:30,290
So we can use the keyword, use.

59
00:03:30,290 --> 00:03:35,040
So we'll say use, and then what we want to
use is $name.

60
00:03:35,040 --> 00:03:41,890
So now we can go through and say hello and
then $name.

61
00:03:41,890 --> 00:03:44,660
But we want to make sure we change this to
double quotes because we

62
00:03:44,660 --> 00:03:49,080
are evaluating name and single quotes
don't do evaluation.

63
00:03:49,080 --> 00:03:52,010
So let's go ahead and hit Save and see if
this does what we expect.

64
00:03:53,670 --> 00:03:54,760
Refresh.

65
00:03:54,760 --> 00:03:56,540
And then it says, hello Mike.

66
00:03:56,540 --> 00:04:00,870
So in an anonymous function, instead of
passing through an argument anonymously,

67
00:04:00,870 --> 00:04:04,680
we'll just use something outside of the
function scope.

68
00:04:04,680 --> 00:04:08,280
So name would be outside the function
scope defined on line three.

69
00:04:08,280 --> 00:04:12,750
We utilize the use keyword and then pass
through $name that way