Projects in Julia

Even for a personal project, we recommend to make a simple Julia package (like in python you use virtual environment). This is a simple tutorial to help you coding an app in Julia.


You need to have Julia installed and a GitHub account.

Creating the Julia Package

We'll be using PkgSkeleton.jl which allows to simplify the creation of packages. First check your git configuration (as it will be used to create the package) with:

git config --list

You should see your, your and github.user, if not then use for example:

git config --global "firstname lastname"
git config --global "bla.bla@domain.ext"
git config --global github.user "ghuser"

Now, I describe the steps used to make a package called KalmanAD.jl, you need to replace KalmanAD.jl by the name of your package and mlelarge by your github.user! This particular package has nothing specific but since naming (with extension .jl for example) can be a little bit tricky, if you have any doubt, you can have a look at the package on GitHub to see how things are organized...

Move to the folder where you want to create your package: we will use Julia to create a folder KalmanAD.jl with the right structure. For this, start Julia and enter the package installation mode by typing ] then run (to exit the pkg> mode just type on Backspace)

pkg> add PkgSkeleton
julia> using PkgSkeleton
julia> PkgSkeleton.generate("KalmanAD.jl")

Now, when your exit Julia, you should have a folder KalmanAD.jl with some files and folders in it.

Connecting to GitHub

Go on and create a repository with the same name: KalmanAD.jl by following these steps (make it public).

On your computer, inside your KalmanAD.jl run the following commands:

git add . && git commit -m "initial commit"
git remote add origin
git branch -M main
git push -u origin main

The first command add the files created by PkgSkeleton and commit them. The last 3 commands are connecting your git repo to GitHub (of course you need to replace mlelarge and KalmanAD.jl by the appropriate values). Now, you should see on your GitHub account the repository you created on your computer.

Start coding

You have 3 sub-folders in your Package docs, src and test. Your code should be in the src subfolder. In particular, in the src folder there should be a file with the same name as the package, (i.e. KalmanAD.jl here) and this file contains:

module KalmanAD
end #module

This file will need to be modified as it will define the module of your package.

Now, when you start coding, you will use other Julia packages. For example, you can see in KalmanAD.jl that I am using the package LinearAlgebra. So I need to add it as a dependency of my own package (a bit like a virtual env in python), to do so you need to run Julia and activate the environment of your package with the command: julia --project. Now if you type ], you should see:

(KalmanAD) pkg>

and you can now add the packages you need, for example:

(KalmanAD) pkg> add LinearAlgebra

as a result this will modify (automatically) the files Project.toml and Manifest.toml. Next time, you commit, do not forget to add these files.

Start testing

In the test folder, there is a runtest.jl file that should contain the tests for your package. You need to use the macro @test which will raise an error if the expression does not evaluate to true. In order to run your tests, you can use:

julia --project test/runtest.jl

Start documenting