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The `testing` branch we created in the previous video is an example of a __topic branch__. A "topic" is defined as "a matter dealt with in a book or article". Examples of topics in your _code_ might include changing the colors on a website, or adding a new feature to a program. When you're working on new features or bug fixes, it's best to do it on a branch, a topic branch, that deals exclusively with commits for that feature.
The testing branch we created in the previous video is an example of a topic branch. A "topic" is defined as "a matter dealt with in a book or article". Examples of topics in your code might include changing the colors on a website, or adding a new feature to a program. When you're working on new features or bug fixes, it's best to do it on a branch, a topic branch, that deals exclusively with commits for that feature.
$ git branch color-theme
$ git branch reply-all
- Our decoder library doesn't actually contain any translations from numbers to letters yet. I'm going to add some now, for the letters A through E.
1 => 'A',
2 => 'B',
3 => 'C',
4 => 'D',
5 => 'E',
- But this is a new topic within our code, so we don't just want to commit it to an existing branch. We want to create a new branch before we make any commits.
- The new branch will be based on whatever branch is checked out when we create it.
- Because we're going to be merging this code into the
masterbranch later, we want our new branch to be based on themasterbranch. - So we need to be sure the
masterbranch is checked out:git checkout master - We'll show you what would happen if a different topic branch were checked out in the next video.
- Because we're going to be merging this code into the
- Now let's create a branch to hold our new letter translations.
- This time, I'm going to use a shortcut that creates and checks out the new branch all in one step.
- We don't run
git branchat all. - Instead, we add the
-bcommand-line option to thegit checkoutcommand:git checkout -b add-letters - This will cause the branch we specify to be created before checking it out.
- We don't run
- If you run
git branch, then as before you'll see our newadd-lettersbranch. It already has a star in front of it, showing that it's checked out. - Now let's make a commit to our new branch.
- I'll stage the file that includes our changes:
git add decoder.rb - And commit it:
git commit -m "Add A-E" - If I run
git lognow, we'll see the commit for thisadd-lettersbranch:git log - As before, the new commit is added at the top, and the
add-lettersbranch is moved to point to it. - The
masterbranch stays pointing at the same commit it was before.
- I'll stage the file that includes our changes:
commit af94e112210c0c7b15f8ed94ca51d090dfe56587 (HEAD -> add-letters)
Author: Jay McGavren <me@example.com>
Date: Fri Sep 28 13:15:36 2018 -0700
Add A-E
commit 21428a2eee8e55becb6da879228446746ad6f1a8 (master)
Author: Jay McGavren <me@example.com>
Date: Tue Sep 25 08:34:12 2018 -0700
Add main program
commit e40647094c74d64fb7c4dee7351139c3ba644d9c
Author: Jay McGavren <me@example.com>
Date: Tue Sep 25 08:22:59 2018 -0700
Add decode function
- The repository looks like this.
- We've added a new commit, and the new
add-lettersbranch has been moved to point to it. - This
add-lettersbranch is based off themasterbranch, but its commit history is totally separate from thetestingbranch we created earlier.
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The testing branch we created in
the previous video is an example of
0:00
a topic branch.
0:03
A topic is defined as a matter
dealt within a book or article.
0:05
Examples of topics in your code might
include changing the colors on a website
0:10
or adding a new feature to your program.
0:14
When you're working on new features or
bug fixes, it's best to do it on a branch,
0:16
a topic branch that deals exclusively
with commits for that feature.
0:20
Our decoder library doesn't actually
contain any translations from numbers
0:24
to letters yet.
0:29
I'm going to add some now for
the letters A through E.
0:30
But this is a new topic within our code,
so we don't just want to commit it to
0:33
an existing branch, we want to create
a new branch before we make any commits.
0:37
the new branch will be based on whatever
branch is checked out when we create it.
0:42
Because we're going to be merging this
code into the master branch later,
0:47
we want our new branch to be
based on the master branch.
0:49
So we need to be sure the master branch
is checked out, git checkout master.
0:53
We'll show you what would happen if a
different topic branch were checked out in
1:01
the next video.
1:05
Now let's create a branch to hold
our new letter translations.
1:06
This time I'm going to use
a shortcut that creates and
1:10
checks out the new branch all in one step.
1:13
We don't run git branch at all.
1:15
Instead, we add the -b command line
option to the git checkout command.
1:17
Git checkout -b add-letters.
1:21
This will cause the branch we specify
to be created before checking it out.
1:25
If you run git branch, then as before,
you'll see our new add letters branch.
1:30
It already has a star in front of
it showing that it's checked out.
1:35
If you run git log, then as before,
1:39
you'll see the commits from
the new master branch.
1:41
But there's a new add letters branch
pointing to the same commit as
1:43
the master branch.
1:46
Now, let's make a commit
to out new branch.
1:51
I'll stage the file that includes
our changes, git add decoder.rb.
1:53
And I'll commit it with
git commit-m add A-E.
1:59
If I run git log now, we'll see
the commit for this add letters branch.
2:05
As before,
the new commit is added at the top, and
2:09
the add letters branch
is moved to point at it.
2:12
The master branch stays pointing
at the same commit it was before.
2:15
The repository looks like this.
2:21
We've added a new commit and
2:23
the new add-letters branch has
been moved to point to it.
2:24
This add-letters branch is based off the
baster branch, but its commit history is
2:28
totally separate from the testing
branch we created earlier.
2:32
Let my put my terminal and editor side
by side, and I'll show you what I mean.
2:35
Let's check out the testing branch,
git checkout testing.
2:40
You can see that git updates the contents
of the working directory to match
2:44
the contents of the latest
commit on the testing branch.
2:48
Git updates the decoder.rb file with
the version from the commit on the testing
2:52
branch, which doesn't have
our new letter translations.
2:56
And the test_decoder.rb file
doesn't exist in the commit for
2:59
the add-letters branch, but it does in
the commit from the testing branch.
3:03
So git adds that file to
the working directory.
3:07
Now let's run git log.
3:12
You can see that our commit to add the new
letter translation isn't present on
3:15
the testing branch.
3:18
But here are our two commits
that add unit tests.
3:20
If we check out the add letters branch
again, those changes will be reversed.
3:24
The test deoder.rb file doesn't exist on
the add letter branch, so git removes it.
3:30
And the decoder.rb file is updated to
include our letter translations again.
3:37
We can run git log again, and
we'll see that the two commits that had
3:44
unit tests are no longer shown, but the
commit that adds letter translations is.
3:49
Now we have a new add letters branch
which is based off of the master branch.
3:54
But what would happen if we had based
add letters off of a different branch,
3:58
like the testing branch?
4:02
We'll find out in the next video
4:03
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