Store and share your code

Last updated on 2024-06-28 | Edit this page

Estimated time: 40 minutes

Overview

Questions

  • How to upload your code to GitHub?
  • What information to add to make the code reusable?
  • How to contribute to someone’s code?
  • How other people can contribute to your code?

Objectives

  • Upload a Pythia example to a GitHub repository
  • Make sure that it contains all necessary information for its use
  • Test someone’s code and propose improvements
  • Contribute to the code through pull requests
  • Review and approve pull requests to your code

Create a GitHub repository for your Pythia code

During the Pythia sessions, you have exercised with different examples. Upload one of them to GitHub.

Prepare a local repository

Create a local Git repository under your Pythia working directory for one of the examples.

Make sure that the directory has all necessary files to run the example. Make a separate directory without other file if needed. In general, it is a good practice to structure it so that it has subdirectoris for code, inputs and outputs:

$ tree example_dir/
example_dir/
├── code
├── inputs
└── outputs

However, for the Pythia examples, the Makefile is written so that it expects the code files to be at the same level with it. So leave it flat for now.

Move to the directory and initialize it with

BASH 

git init

Test that everything works, i.e compile and run the code.

Remember to compile and run the code in the Pythia container. Start it from the working repository with

BASH 

docker run -v $PWD:/host -w /host -it --rm hepstore/rivet-pythia

Exclude files with .gitignore

Before committing files to the repository, think what files you would like to exclude. Create a .gitignore file with the names of the files that you do not intend to upload.

See .gitignore example files in https://github.com/github/gitignore In our case, you will probably leave out the executable file. If it is called main01 , the contents of the .gitignore file would be

main01

Note that the file starting with dot (.) are not visible with the usual ls commands, use ls -a to see them.

Commit the files

Add the files you want to version and commit them.

Check the status:

BASH 

git status

Note that the executable file defined in the .gitignore file does not appear in the list. Git ignores it as the name says.

Always make sure to add only the files that you want to commit and in case some unwanted file appear in the list of Untracked files, add them to .gitignore (or remove if you do not need them).

Add and commit:

BASH 

git add .
git commit -m "First commit"

Upload the local repository to GitHub

Create a GitHub repository and push your files there.

Go to your GitHub area (https://github.com/[yourgithubname]), choose the “Repositories” tab and click on New.

Choose a repository name, select Public and leave other options as they are. This will create the repository and generate an instruction page, and you can copy the commands under the title “…or push an existing repository from the command line”.

BASH 

git remote add origin git@github.com:[yourgithubname]/[yourreponame].git
git branch -M main
git push -u origin main

Note that the SSH key connected to GitHub is in your local file system, and it is not in the directory that is shared with the container. Therefore, you will not be able to push to your GitHub repository from the container. Do it from your local shell.

Add instructions

Add instructions to your repository so that other people know what your code does and how to use it. Write them in README.md and push them to the GitHub repository.

Good instructions should contain

a brief description of the code

description of the running environment

description of the input parameters

instructions to compile and run

description of the expected output

Write them in a new file called README.md.

Check status:

BASH 

git status

Add and commit:

BASH 

git add .
git commit -m "Add README"

Push to the remote repository:

BASH 

git push origin main

Run someone’s code

Clone someone’s repository and run their code

Ask other participant the address of their GitHub repository and clone it locally.

Note: first move up from your Git repository. Do not nest Git repositories.

Follow their instructions to run the code.

Move to your working area, and use git clone. Copy the repository address from the green Code dropdown menu (ssh tab).

If their repository name is same as yours, give it another name locally:

BASH 

git clone git@github.com:[someoneelse]/[repositoryname].git [localrepositoryname]

Follow the instructions in the README to understand the code, and to compile and run it. Is the output as expected?

Contribute to someone’s code

Open a GitHub issue to suggest improvements

Suggest an improvemnt to the code or to instructions. Open a GitHub issue in the repository.

Code to the GitHub repository of the code you cloned and find the “Issues” tab. Click on New issue:

Write a descriptive title.

In the issue text, always explain

what you observed

what you expect

how to reproduce (if it is a code issue)

Be respectful and polite.

To contribute, there are two approaches:

Callout

Fork and pull

In the fork and pull model, anyone can fork an existing repository and push changes to their personal fork. You do not need permission to the source repository to push to a user-owned fork. The changes can be pulled into the source repository by the project maintainer. When you open a pull request proposing changes from your user-owned fork to a branch in the source (upstream) repository, you can allow anyone with push access to the upstream repository to make changes to your pull request. This model is popular with open source projects as it reduces the amount of friction for new contributors and allows people to work independently without upfront coordination.

Callout

Shared repository

In the shared repository model, collaborators are granted push access to a single shared repository and topic branches are created when changes need to be made. Pull requests are useful in this model as they initiate code review and general discussion about a set of changes before the changes are merged into the main development branch. This model is more prevalent with small teams and organizations collaborating on private projects.

Provide a fix to the issue you described

As the code is in someone’s personal GitHub area, fork and pull approach seems appropriate. You do not need to be added as a collaborator to the repository to propose changes. It is up to them to accept your changes or not.

Fork the code to your own GitHub area in the GitHub Web UI. Change the remote of your existing Git repository.

In the GitHub Web UI, find the “Fork” button in the GitHub repository to which you want to contribute. Create a fork.

Then connect your local repository to that for:

Either change the origin of your existing local repository (cloned directly from its original area) and check the eventual updates

BASH 

git remote rm origin
git remote add git@github.com:[yourgithubname]/[repositoryname].git
git pull origin main

or remove the existing local repository (rm -rf) and clone it again from your fork.

Then fix the issue in your local repository.

If it is in the code, compile and run (remember, in the container!!)

Check status:

BASH 

git status

Add and commit:

BASH 

git add .
git commit -m "describe the change"

Push to the remote repository which is now your fork:

BASH 

git push origin main

In the GitHub Web UI of your forked repository, will find a message about number of commits ahead.

Click on Contribute and click on the green button “Open pull request”.

Check that the base repository is what you want.

Modify the title if needed and a description.

If you add closes #[issuenumber] in the title or in the description, the issue will get closed automatically once once the pull request is merged. You can find the issue number in the in the list of issues in the GitHub Web UI.

Click on the green button “Create pull request”.

Accept a pull request

The pull request appears in the repository to which you contributed.

Maybe someone has forked your repository and proposes a pull request.

Review and accept the pull request

In the GitHub Web UI of the repository, find the list of pull requests.

Choose the pull request.

In the “Files changed” tab, you can see the changes.

You can open a comment for a specific line in the changes by clicking on + at the start of the line.

Find the green “Review changes” button on the right. You can comment, and as the owner of the repository, approve or request changes.

In the “Conversation” tab, you can “Merge pull request” and “Confirm merge”.

Key Points

  • It is easy to store and share your code through a GitHub repository.
  • Clear instructions make it possible for other people to run your code.
  • You can contribute to other repositories from your own fork, or directly to the repository if you are added as a collaborator.
  • Other people can contribute to your repository through pull requests from their own fork.