Git for session demos

Question

I often use git in session demos, in order to show step by step software development. Until now, I defined tags for developmental milestones and I used to checkout to go from one step to another. But this is not a good idea: I sometimes want to update certain steps and the transition from a tag to another one is not always intuitive.

I found some interesting ways to try to improve things. At https://coderwall.com/p/ok-iyg, next and prev aliases are defined to facilitate navigation between steps, but these aliases are defined on commits, that does not solve the problems of updates steps. At http://www.damirscorner.com/UsingGitInSessionDemos.aspx, the steps are based on branches, which I think is a better solution to allow updates. It is possible to redefine commands like next and prev in this context, possibly using a naming convention for branches (step1, step2 ... for example).

But in order to get fully functional controls, one could ideally add some operations, such as: the possibility of an amendment to a branch and the merge with one or more other branches (either previous or next ones), or the check just before leaving a step that the working directory is clean, with a proposal to either clean or commit.

Do you know an extension / workflow / use case in this spirit that could help me to reach faster the environment I want?

Thanks in advance!

Answer 1

One fairly simple solution would be to create these two aliases (presuming a *nix environment):

git config alias.prev prev`git branch | grep '\*' | cut -d' ' -f2`
git config alias.next next`git branch | grep '\*' | cut -d' ' -f2`

Those will resolve into:

git prevbranch
git nextbranch

...where branch is the name of the current branch - e.g. if you're on the master branch and call git next, it'll resolve to and run git nextmaster. Then you can just make repo-local aliases with those prev/next names.

If you want git next to take you from step1 to step2 and git prev to take you from step2 to step1, then make these aliases:

git config alias.nextstep1 'checkout step2'
git config alias.prevstep2 'checkout step1'

This turns things into a git-like system of loosely-connected nodes, connected only by named references, which are easily editable in .git/config under the [alias] section, ready for use in any environment, and contained away from the files in the repo proper.

Note that the config file does not travel with repos (i.e. when cloning, fetching, pushing, or pulling), so you'll need to bring the .git folder with you, or at least the .git/config file, or just remake those aliases wherever you are.