l2_2-git.jl

#src # This is needed to make this run as normal Julia file
using Markdown #src

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#nb # _Lecture 2_: Git
md"""
# A brief intro to Git

Git is a version control software, useful to
- keep track of your progress on code (and other files)
- to collaborate on code
- to distribute code, to onself (on other computers) and others
"""

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md"""
## Previous experience

You are familiar with git already:

![git-survey](./figures/l2_survey-git-question.png)
"""

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md"""
Questions:
- how often do you use git?
- who has git installed on their laptop?
- do you use: `commit`, `push`, `pull`, `clone`?
- do you use: `branch`, `merge`, `rebase`?
- GitHub/GitLab etc?
"""

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md"""
## A brief git demo session

Please follow along!

If you don't have git installed, head to [JupyterHub (within Moodle)](https://moodle-app2.let.ethz.ch/course/view.php?id=18084) and open a terminal. (And do install it on your computer!)

- git setup:

```sh
git config --global user.name "Your Name"
git config --global user.email "youremail@yourdomain.com"
```
- make a repo (`init`)
- add some files (`add`, `commit`)
- do some changes (`commit` some more)
- make a feature branch (`branch`, `diff`, `difftool`)
- merge branch (`merge`)
- tag (`tag`)
"""

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md"""
### Further reading

There are (too) many resources on the web...
- book: [https://git-scm.com/book/en/v2](https://git-scm.com/book/en/v2)
- videos: [https://git-scm.com/doc](https://git-scm.com/doc)
- cheat sheet (click on boxes) [https://www.ndpsoftware.com/git-cheatsheet.html#loc=workspace;](https://www.ndpsoftware.com/git-cheatsheet.html#loc=workspace;)
- get out of a git mess: [http://justinhileman.info/article/git-pretty/git-pretty.png](http://justinhileman.info/article/git-pretty/git-pretty.png)

## Other tools for git
There is plenty of software to interact with git, graphical, command line, VSCode, etc.  Feel free to use those.

But we will only be able to help you with vanilla, command-line git.
"""

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md"""
## Getting started on GitHub (similar on GitLab, or elsewhere)

GitHub and GitLab are social coding websites
  - they host code
  - they facilitate for developers to interact
  - they provide infrastructure for software testing, deployment, etc
"""

#nb # > 💡 Note: ETH has a GitLab instance which you can use with your NETHZ credentials [https://gitlab.ethz.ch/](https://gitlab.ethz.ch/).
#md # \note{ETH has a GitLab instance which you can use with your NETHZ credentials [https://gitlab.ethz.ch/](https://gitlab.ethz.ch/).}

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md"""
Question: who has a GitHub account?

Let's make one (because most of Julia development happens on GitHub)

[https://github.com/](https://github.com/) -> "Sign up"
"""

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md"""
### GitHub setup

Make such that you can push and pull without entering a password

![github-bar](./figures/l2_github-bar.png)

- local: tell git to store credentials: `git config --global credential.helper cache`
  (this may not be needed on all operating systems, potentially a built-in password/credential
   manager will do this automatically)
- github.com:
  - "Settings" -> "Developer settings" -> "Personal access tokens" -> "Generate new token"
    - Give the token a description/name and select the scope of the token
    - I selected "repo only" to facilitate pull, push, clone, and commit actions
  - -> "Generate token" and copy it (keep that website open for now)
"""

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md"""
## Let's get our repo onto GitHub

![github-bar](./figures/l2_github-bar.png)

- create a repository on github.com: click the "+"
- local: follow setup given on website
- local: `git push`
  - here enter your username + the **token** generated before
"""

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md"""
## Work with other people: pull request (PR)

When you contribute new code to a repo (in particular a repo which other people work on too), the new code is submitted via a "pull request".  This code is then in a separate branch.  A pull request then makes a web-interface where one can review the changes, request amendments and finally merge the code.

In a repo with write permission, the use following work-flow:
- make a branch and switch to it: `git switch -c some-branch-name`
- make changes, add files, etc. and commit to the branch.  You can have several commits on the branch.
- push the branch to Github
- on the Github web-page a bar with a "open pull request" should show: click it
- if you got more changes, just commit and push them to that branch
- when happy merge the PR

This work-flow you will use to submit homework for the course.
"""

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md"""
## Work with other peoples code: fork

![github-bar](./figures/l2_github-bar.png)

For repos without write access, to contribute do:

- fork a repository on github.com (top right)
- make a branch on that fork and work on it
- push that to github and open a PR with respect to that fork
- (not needed in this lecture course)
"""

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md"""
## Git: questions?

![git-me](./figures/l2_git-me.png)
"""