Developers need to memorize a whole bunch of magic command-line incantations. And these incantations change from time to time! Typically, their lives are made simpler by a Makefile, but Makefiles can be convoluted, are not written in Python, and are hard to extend. The rationale behind devpy is therefore to provide a simple interface for common development tasks. It comes with a few common build commands out the box, but can easily be customized per project.

As a curiosity: the impetus behind developing the tool was the mass migration of scientific Python libraries (SciPy, scikit-image, and NumPy, etc.) to Meson, after distutils was deprecated. When many of the build and installation commands changed, it made sense to abstract away the nuisance of having to re-learn them.

Settings are in your project's pyproject.toml. As an example, see the [tool.devpy] section of an example pyproject.toml.

The [tool.devpy] section should contain:

package = 'pkg_importname'  # used by pytest
commands = ['devpy.build', 'devpy.test']

python -m devpy

On Unix-like systems, you can also copy the dev.py script to the root of your project directory, and launch it as:

./dev.py

  build    🔧 Build package with Meson/ninja and install to `build-install`
  ipython  💻 Launch IPython shell with PYTHONPATH set
  python   🐍 Launch Python shell with PYTHONPATH set
  shell    💻 Launch shell with PYTHONPATH set
  test     🔧 Run tests

devpy can invoke custom commands. These commands define their own arguments, and have access to the pyproject.toml file for further configuration.

See, e.g., the example custom command.

Add custom commands to the commands variable in the [tool.devpy] section of pyproject.toml as follows:

commands = [..., '.devpy/cmds.py:example']

Here, the command is stored in .devpy/cmds.py, and the function is named example.

Custom commands can access the pyproject.toml as follows:

from devpy import util

@click.command()
def example():
    """Command that accesses `pyproject.toml` configuration"""
    config = util.get_config()
    print(config["tool.devpy"])

Once you have several commands, it may be useful to organize them into sections. In pyproject.toml, instead of specifying the commands as a list, use the following structure:

[tool.devpy.commands]
"Build" = ["devpy.build", "devpy.test"]
"Environments" = ["devpy.shell", "devpy.ipython", "devpy.python"]

These commands will then be rendered as:

Build:
  build  🔧 Build package with Meson/ninja and install
  test   🔧 Run tests

Environments:
  shell    💻 Launch shell with PYTHONPATH set
  ipython  💻 Launch IPython shell with PYTHONPATH set
  python   🐍 Launch Python shell with PYTHONPATH set

The dev.py tool was proposed for SciPy by Ralf Gommers and implemented by Sayantika Banik, Eduardo Naufel Schettino, and Ralf Gommers (also see Sayantika's blog post). Inspired by that implementation, devpy (this package) is a minimal rewrite by Stéfan van der Walt, that aims to be easily extendable so that it can be used across ecosystem libraries.