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Developer Guide


This chapter is only interesting if you intend to make changes to the code of djinni generator

Building from source

Build dependencies

  • Java JDK 8 or 11
  • sbt


To build once:

sbt compile

To automatically re-build on every change, open the sbt shell & prefix compile with ~

$ sbt
sbt:djinni> ~compile


sbt "run
    --idl input.djinni
    --cpp-out out/cpp
    --java-out out/java/src
    --jni-out out/java/jni
    --objc-out out/objc
    --py-out out/python
    --pycffi-out out/cffi
    --c-wrapper-out out/cwrapper
    --cppcli-out out/cppcli"
sbt "run --help"  # show all options

It is important to put run and all arguments in ", to be able to pass arguments to the executed jar!

Running Tests

sbt IntegrationTest/test

For testing, the djinni target needs to exist, so run sbt assembly before. This is also required when you do development on the generator. Always run sbt assembly before doing integration testing!


Create a binary like the one that is published on github releases:

sbt assembly

This will generate a standalone, self-executing jar in target/bin. You can run the jar like this:

./djinni --help


The resulting binary still requires Java to be able to run! Details on how the self-executing jar works.

Code Formatting

All scala- and sbt-files need to be formatted with the scala-fmt plugin.

To format all files, execute sbt scalafmtAll.

The version of the scala format tool can be changed in the file .scalafmt.conf and the version of the scala plugin can be changed in the file project/plugins.sbt.

To change the code formatter configurations, put all configuration options inside .scalafmt.conf. See all configuration options here.

You can check if the formatter is working with the command sbt scalafmtCheck.

All available tasks of the code formatter plugin can be checked here.

Project Structure

├── (1)
├── LICENSE (2)
├── (3)
├── build.sbt (4)
├── docs (5)
│   └── ...
├── mkdocs.yml (6)
├── project (7)
│   └── ...
└── src (8)
    ├── it (9)
    │   ├── resources (10)
    │   │   ├── expected (11)
    │   │   │   └── ...
    │   │   └── result (12)
    │   │       └── ...
    │   └── scala
    │       └── djinni (13)
    │           └── ...
    └── main
        └── scala
            └── djinni (14)
                └── ...
  1. Project Code of Conduct.
  2. Project License (Apache License).
  3. Readme file.
  4. Sbt build configuration.
  5. Documentation folder containing markdown documentation that will be rendered with MkDocs.
  6. MkDocs configuration. Will be included by the repository and published to
  7. Sbt configuration.
  8. Sources folder.
  9. Integration testing directory.
  10. Resources for integration tests.
  11. Folder containing expected outcomes of the djinni generator. These files are matched against the real result of the generator in the integration tests.
  12. Folder that will be used for generator outputs in the integration tests. Files in here should not be checked in to source control.
  13. Folder containing the integration testing code.
  14. djinni-generator source code.

Preview Documentation

The documentation in docs will be rendered as a part of

You can preview how the docs will look like:

# install required dependencies
pip install -r mkdocs-requirements.txt
# render a live preview of the docs under
mkdocs serve

Release process

To release a new version of the generator, the following steps must be followed:

  1. Create a new release on Github. Set a tag version following semantic versioning rules (v<MAJOR>.<MINOR>.<PATCH>) and describe what has changed in the new version.
  2. Wait. The Github "release" Action will automatically build the project and upload the resulting binaries to the release.
  3. Create a PR to the conan-center-index to publish the new version to Conan Center.
  4. Update the homebrew tap to make it point to the newest version here.

Last update: March 16, 2022