A Worked Example

Maintainer#

Let’s say Alice maintains a library:

1   mkdir -p lgthw_submodules
2   cd lgthw_submodules
3   mkdir alicelib
4   cd alicelib
5   git init
6   echo 'A' > file1
7   git add file1
8   git commit -am 'A'
9   git checkout -b experimental      # Branch to experimental
10  echo 'C - EXPERIMENTAL' >> file1
11  git commit -am EXPERIMENTAL
12  git checkout master
13  echo 'B' >> file1
14  git commit -am 'B'

History#

Alice’s library’s history looks like this:

Using code from a specific branch#

Now Bob wants to use Alice’s library for his own code but specifically wants to use what’s on the experimental branch.

One option is to copy the code over directly, but that seems to be against the spirit of Git.

If an improvement is made on the experimental branch or Bob wants to move later to follow what’s on the master branch, then he must copy over the code he wants. For one file, it might be manageable. But managing this will be completely impractical for a more realistic and large project.

Another option is to check out the code in another folder and link to it in some predictable way in the code (e.g., your code might run source ../alice_experimental). Again, this causes management problems, as the user checking out the source must remember to keep code outside this Git repository in a certain place for it all to work.