1
00:00:04,080 --> 00:00:06,080
-Hi everyone. In this video,
we are going to look

2
00:00:06,400 --> 00:00:08,240
at how we can use the tool Metacello

3
00:00:08,920 --> 00:00:12,240
to load external packages
inside your Pharo environment.

4
00:00:12,560 --> 00:00:16,000
The package we are going to look at
is called "Containers-Stack".

5
00:00:16,320 --> 00:00:21,200
It basically consists
of stack implementations

6
00:00:21,520 --> 00:00:25,600
with push, size, top,
and pop variations.

7
00:00:25,920 --> 00:00:31,520
A really simple stack implementation.
You can see in the paragraph Loading

8
00:00:31,840 --> 00:00:36,360
that you will have a piece of code
that is calling Metacello

9
00:00:36,680 --> 00:00:39,560
along with a baseline
and repository arguments.

10
00:00:39,880 --> 00:00:42,880
We are going to look into the baseline
a bit later on.

11
00:00:43,200 --> 00:00:48,600
But if we look at the repository, it is
basically this URL slightly modified.

12
00:00:48,920 --> 00:00:52,800
Let's just try to copy this
into our Pharo environment.

13
00:00:53,960 --> 00:00:56,640
Navigate to our Pharo environment,
System Browser open.

14
00:00:57,160 --> 00:00:59,520
We are going to look for containers.

15
00:00:59,840 --> 00:01:01,960
We have the definitions
of containers, rings.

16
00:01:02,280 --> 00:01:05,520
If we go to Pharo,
Tools then Playground,

17
00:01:05,840 --> 00:01:10,800
you can paste the code I just copied
and then, if we execute it with Cmd+D,

18
00:01:11,120 --> 00:01:13,120
you can see
that it is loading everything,

19
00:01:13,440 --> 00:01:18,200
and we can now see those 3 new packages.
Basically, we have the Containers-Stack

20
00:01:18,520 --> 00:01:21,800
where there is the actual
implementation of the stack.

21
00:01:22,120 --> 00:01:26,760
Then a test package which we can check
if it is green. It is, great.

22
00:01:27,080 --> 00:01:30,960
And we have got
BaselineOfContainersStack.

23
00:01:31,280 --> 00:01:33,880
This was what I was talking about.
Basically,

24
00:01:34,200 --> 00:01:40,200
baselines are classes which only have
one method called baseline.

25
00:01:40,520 --> 00:01:47,600
It will specify which packages every
package in your actual project will need

26
00:01:47,920 --> 00:01:49,040
in order to work correctly.

27
00:01:49,360 --> 00:01:54,680
Here, we can see that we have got a spec
package for the Containers-Stack-Tests

28
00:01:55,000 --> 00:01:57,840
that requires the actual
Containers-Stack in order to work.

29
00:01:58,160 --> 00:02:01,440
It is a real simple baseline,
but this will help you

30
00:02:01,760 --> 00:02:04,760
specify how your project
will work altogether.

31
00:02:05,080 --> 00:02:07,400
We can see, if we go back
to the GitHub page,

32
00:02:07,720 --> 00:02:11,000
that "If you want to depend on it".
So, basically,

33
00:02:11,320 --> 00:02:14,680
if you want to use Containers-Stack
in a bigger project,

34
00:02:15,000 --> 00:02:17,400
you can use the spec baseline
Containers-Stack

35
00:02:17,720 --> 00:02:18,720
with spec repositories.

36
00:02:19,040 --> 00:02:21,520
So, this is something you have
to include in your baseline

37
00:02:21,840 --> 00:02:24,360
in order to depend on this project here.

38
00:02:25,240 --> 00:02:27,320
We learned how to use Metacello

39
00:02:27,640 --> 00:02:31,840
in order to load GitHub repositories
with a baseline.

40
00:02:32,160 --> 00:02:37,160
A baseline is something that specifies
what a project needs

41
00:02:37,480 --> 00:02:40,880
in terms of dependencies
in order to load correctly.