mruby is an open-source project which is looking forward to each contribution. Contributors agree to license their contribution(s) under MIT license.

Your Pull Request

To make it easy to review and understand your change please keep the following things in mind before submitting your pull request:

Work on the latest possible state of mruby/master
Create a branch which is dedicated to your change
Test your changes before creating a pull request (rake test)
If possible write a test case which confirms your change
Don't mix several features or bug-fixes in one pull request
Create a meaningful commit message
Explain your change (i.e. with a link to the issue you are fixing)
Use mrbgem to provide non ISO features (classes, modules and methods) unless you have a special reason to implement them in the core

pre-commit

A framework for managing and maintaining multi-language pre-commit hooks. pre-commit can be installed with pip, curl, brew or conda.

You need to first install pre-commit and then install the pre-commit hooks with pre-commit install. Now pre-commit will run automatically on git commit!

It's usually a good idea to run the hooks against all the files when adding new hooks (usually pre-commit will only run on the changed files during git hooks). Use pre-commit run --all-files to check all files.

To run a single hook use pre-commit run --all-files <hook_id>

To update use pre-commit autoupdate

Sometimes you might need to skip one or more hooks which can be done with the SKIP environment variable.

$ SKIP=yamllint git commit -m "foo"

For convenience, we have added pre-commit run --all-files, pre-commit install and pre-commit autoupdate to both the Makefile and the Rakefile. Run them with:

make check or rake check
make checkinstall or rake checkinstall
make checkupdate or rake checkupdate

To configure pre-commit you can modify the config file .pre-commit-config.yaml. We use GitHub Actions to run pre-commit on every pull request.

pre-commit quick links

Docker

We have both a Dockerfile and docker-compose.yml files in the repository root. You can run these with the command line or use Docker Desktop.

The Docker image is running Debian bullseye with Ruby and Python installed. You can build the Docker image with:

$ docker-compose build test

So far we just have one service: test. Running the default docker-compose command will create the Docker image, spin up a container and then build and run all mruby tests.

The default docker-compose command is:

$ docker-compose -p mruby run test

You can also use Make or Rake to run the default docker-compose command from above:

make composetest
rake composetest

List your Docker images with:

$ docker images
REPOSITORY   TAG       IMAGE ID       CREATED          SIZE
mruby-test   latest    ec60f9536948   29 seconds ago   1.29GB

You can also run any custom docker-compose command which will override the default. For example to run pre-commit run --all-files type:

$ docker-compose -p mruby run test pre-commit run --all-files

For convenience, you can also run pre-commit with:

make composecheck
rake composecheck

The bonus of running pre-commit with docker-compose is that you won't need to install pre-commit and the hooks on your local machine. And that also means you won't need to install brew, conda or pip.

Note limitation: currently running pre-commit with docker-compose we skip the check-executables-have-shebangs hook.

Two more examples of custom docker-compose commands are:

$ docker-compose -p mruby run test ls
$ docker-compose -p mruby run test rake doc:api

If you want to test using a different docker-compose YAML config file you can use the -f flag:

$ docker-compose -p mruby -f docker-compose.test.yml run test

Spell Checking

We are using pre-commit to run codespell to check code for common misspellings. We have a small custom dictionary file codespell.txt.

Coding conventions

How to style your C and Ruby code which you want to submit.

C code

The core part (parser, bytecode-interpreter, core-lib, etc.) of mruby is written in the C programming language. Please note the following hints for your C code:

Comply with C99 (ISO/IEC 9899:1999)

mruby should be highly portable to other systems and compilers. For this it is recommended to keep your code as close as possible to the C99 standard (http://www.open-std.org/jtc1/sc22/WG14/www/docs/n1256.pdf).

Visual C++ is also an important target for mruby (supported version is 2013 or later). For this reason features that are not supported by Visual C++ may not be used (e.g. z of strftime()).

NOTE: Old GCC requires -std=gnu99 option to enable C99 support.

Reduce library dependencies to a minimum

The dependencies to libraries should be kept to an absolute minimum. This increases the portability but makes it also easier to cut away parts of mruby on-demand.

Insert a break after the function return value:

int
main(void)
{
  ...
}

Ruby code

Parts of the standard library of mruby are written in the Ruby programming language itself. Please note the following hints for your Ruby code:

Comply with the Ruby standard (ISO/IEC 30170:2012)

mruby is currently targeting to execute Ruby code which complies to ISO/IEC 30170:2012 (https://www.iso.org/iso/iso_catalogue/catalogue_tc/catalogue_detail.htm?csnumber=59579), unless there's a clear reason, e.g. the latest Ruby has changed behavior from ISO.

Building documentation

mruby API

YARD - YARD is a documentation generation tool for the Ruby programming language
yard-mruby - Document mruby sources with YARD
yard-coderay - Adds coderay syntax highlighting to YARD docs

C API

Doxygen - Generate documentation from source code
Graphviz - Graphviz is open source graph visualization software