A very central feature of git is having branches, which allow you to work on multiple features independently, and then merging the features into the same codebase later.
We usually use branches to allow multiple people to work on the same codebase and to test different new features without affecting other features. Then, when we are sure that our code works, we can merge it in the main branch.
To figure out what branch you are currently on, use git status. This will show the branch name you are currently on, along with a bunch of other information about the status of the project.
To create a new branch and start working on it,
git branch branch_name # create a new branch called branch_name
git switch branch_name # switch to the branch called branch_name
# or, you can use the following shortcut which does the same thing as the lines above
git switch --create branch_name # create a new branch, and switch to itNow, you can make any edits to your previous code, and commit it to this branch. And you can git switch to the previous branch to make the changes go away. When you switch back to this branch, the changes will be restored!
To begin, create a branch called branching and switch to it. This will be our principle branch for now.
Then, create a branch called hello_world and switch to it. Then, create a hello world program in any language, and save the file in a directory called hellos. Commit this change.
Now, switch to branching and create a branch called hello_git. Create a program that prints Hello, git! and commit it in hellos folder in this branch. Remember to give different names to both programs(for example, hello_world.py and hello_git.py)
You should now have three branches: branching, hello_world, and hello_git. We will now merge the branches into branching so that all changes are reflected in the principle branch.
To start, make sure you are in the branching branch. Then, you can simply git merge hello_world to merge the branch into branching. Because the branching branch did not have any new changes, the update will be performed via a 'fast-forward', where the newer commits from hello_world are copied and pasted onto master(for efficiency, git actually just moves some pointers around, but we don't need to worry about that).
However, scenarios like merging hello_git into the new branching are far more common. Here, branching has newer commits(adding hello_world), and hello_git has newer commits(adding hello_git). So, we say that the branches have diverged. In this case, merging is slightly trickier.
After making sure that you are on branching, git merge hello_git to merge the branch into branching. Git is pretty smart, and will see that since you have modified different files, you can simply copy both in the same folder. Merging changes made in the same file is sometimes trickier, and we'll practice this more complicated scenario later.
You will have to specify a commit message to describe this merge, and you are done!
Push the changes and create a PR to the original repository. You will have to switch to the branching branch in the browser before you open the PR.
See SQUASH_AND_MERGE.md