developing.md

Developing

Developers are strongly encouraged to use nix for managing the projects dependencies. This makes setup completely hassle free.

Nix Dev Shell

This requires installing Nix. To access the shell simply run:

# NOTE: you will have to enable the flake and nix-command experimental features.
nix develop

Additionally, the development environment can be loaded automatically when inside the project directory using direnv. After install, simply run:

direnv allow .

Editors like VS Code have extensions like direnv for interfacing with the direnv shell. This is can be used so that non-terminal based text editors pick up on the dependencies provided by the nix dev shell.

Note for Auto-Completion

Because this project uses bleeding edge C++, you may need to override the clangd version being used by your editor to version 19+. Otherwise, clangd will choke on any code which uses C++ 26 features.

CMake Developer Mode

Build system targets that are only useful for developers of this project are hidden if the dius_DEVELOPER_MODE option is disabled. Enabling this option makes tests and other developer targets and options available. Not enabling this option means that you are a consumer of this project and thus you have no need for these targets and options.

Developer mode is always set to on in CI workflows.

Presets

This project makes use of presets to simplify the process of configuring the project. As a developer, you are recommended to always have the latest CMake version installed to make use of the latest Quality-of-Life additions.

You have a few options to pass dius_DEVELOPER_MODE to the configure command, but this project prefers to use presets.

As a developer, you should create a CMakeUserPresets.json file at the root of the project:

{
  "version": 2,
  "cmakeMinimumRequired": {
    "major": 3,
    "minor": 21,
    "patch": 0
  },
  "configurePresets": [
    {
      "name": "dev",
      "binaryDir": "${sourceDir}/build/dev",
      "inherits": ["dev-mode", "docs", "ci-<os>"],
      "cacheVariables": {
        "CMAKE_BUILD_TYPE": "Debug"
      }
    }
  ],
  "buildPresets": [
    {
      "name": "dev",
      "configurePreset": "dev",
      "configuration": "Debug"
    }
  ],
  "testPresets": [
    {
      "name": "dev",
      "configurePreset": "dev",
      "configuration": "Debug",
      "output": {
        "outputOnFailure": true
      }
    }
  ]
}

You should replace <os> in your newly created presets file with the name of the operating system you have, which may be win64, linux or darwin. You can see what these correspond to in the CMakePresets.json file.

CMakeUserPresets.json is also the perfect place in which you can put all sorts of things that you would otherwise want to pass to the configure command in the terminal.

Note Some editors are pretty greedy with how they open projects with presets. Some just randomly pick a preset and start configuring without your consent, which can be confusing. Make sure that your editor configures when you actually want it to, for example in CLion you have to make sure only the dev-dev preset has Enable profile ticked in File > Settings... > Build, Execution, Deployment > CMake and in Visual Studio you have to set the option Never run configure step automatically in Tools > Options > CMake prior to opening the project, after which you can manually configure using Project > Configure Cache.

Configure Build and Test

If you followed the above instructions, then you can configure, build and test the project respectively with the following commands from the project root on any operating system with any build system:

cmake --preset=dev
cmake --build --preset=dev
ctest --preset=dev

If you are using a compatible editor (e.g. VSCode) or IDE (e.g. CLion, VS), you will also be able to select the above created user presets for automatic integration.

Please note that both the build and test commands accept a -j flag to specify the number of jobs to use, which should ideally be specified to the number of threads your CPU has. You may also want to add that to your preset using the jobs property, see the presets documentation for more details.

Developer Mode Targets

These are targets you may invoke using the build command from above, with an additional -t <target> flag:

coverage

Available if ENABLE_COVERAGE is enabled. This target processes the output of the previously run tests when built with coverage configuration. The commands this target runs can be found in the COVERAGE_TRACE_COMMAND and COVERAGE_HTML_COMMAND cache variables. The trace command produces an info file by default, which can be submitted to services with CI integration. The HTML command uses the trace command's output to generate an HTML document to <binary-dir>/coverage_html by default.

docs

Available if BUILD_DOCS is enabled. Builds to documentation using Doxygen. The output will go to <binary-dir>/docs/html by default (customizable using DOXYGEN_OUTPUT_DIRECTORY).

di Library

When using the nix environment, the di library is automatically available to the CMake build. However, this copy is immutable. If you need to make changes to both libraries at once, a custom checkout of di can be used by creating a symbolic link named di in the root of this package. For instance, if your di checkout is in a sibling directory of your dius checkout, run:

ln -s "$(realpath ../di)" di

Justfile

The justfile provides a CLI interface for interfacing with the project, and can be used as an alternative to IDE support for CMake presets for developers with more minimal setups.

The justfile operates on a given CMake preset which is controlled by the PRESET environment variable. This defaults to the dev preset you should've setup already. If you add multiple presets to your CMakeUserPresets.json file, you can select which preset to use interactively by running:

eval $(just choose)

Whenever a new justfile command is run, the selected preset will be auto-configured if the build directory does not exist. Additionally, the compile_commands.json for the build configuration will be symlinked into the project directory. This ensures clangd will be configured properly for your preset (This happens automatically when using a VS Code extension like ms-vscode.cpptools).

Building and running the unit tests is as simple as:

just bt

To format all source files, use:

just format

To see an overview of all just commands, simply run just with no arguments.

just

There are several additional commands which should cover everything necessary to develop the project.