Developer Setup

The source code is hosted on GitHub. Clone the repository with the following command:

git clone

Alternatively, fork the project and clone your own fork. Please submit pull requests on their own separate and meaningfully named branches.

PyperCard does not and never will use or support Python 2. You should use Python 3.6 or above.

If you want to discuss PyperCard, aspects of its design or engage with the wider project please don’t hesitate to join our chat channel. Alternatively, we welcome contributions, bug reports, suggestions and pull requests via our GitHub repository.


We expect everyone participating in the development of PyperCard to act in accordance with the PSF’s Code of Conduct.

Windows, OSX, Linux

Create a virtual environment via your command line:

python3 -mvenv pypercardenv

Activate it:

# Unix-y
source pypercardenv/bin/activate

# Windows

The name pypercard should appear at the start of each line of your command line, to show you’re in the active virtualenv.

Ensure you have the latest version of pip installed:

pip install --upgrade pip

Install all the dependencies for PyperCard with:

pip install -e ".[dev]"

Everything should be working if you can successfully run:

make check

(You’ll see the results from various code quality tools, the test suite and code coverage.)


The PyperCard package distribution, as specified in, declares both runtime and extra dependencies.

The above mentioned pip install -e ".[dev]" installs all runtime dependencies and most development ones: it should serve nearly everyone.

For the sake of completeness, however, here are a few additional details. The [dev] extra is actually the aggregation of the following extras:

  • [tests] specifies the testing dependencies, needed by make test.
  • [docs] specifies the doc building dependencies, needed by make docs.

Addionionally, the following extras are defined:

  • [all] includes all the dependencies in all extras.


Using a virtualenv will ensure your development environment is safely isolated from problematic version conflicts with your system wide version of Python.

If you get into trouble, delete the virtualenv’s directory (that’s pypercardenv in the instructions above) and start again with a fresh install. The virtualenv is best thought of as a disposable sandbox in which you can safely do your development work on PyperCard.

Using make

There is a Makefile that helps with most of the common workflows associated with development. Typing make on its own will list the options thus:

$ make

There is no default Makefile target right now. Try:

make clean - reset the project and remove auto-generated assets.
make pyflakes - run the PyFlakes code checker.
make pycodestyle - run the PEP8 style checker.
make test - run the test suite.
make coverage - view a report on test coverage.
make tidy - tidy code with the 'black' formatter.
make check - run all the checkers and tests.
make dist - make a dist/wheel for the project.
make publish-test - publish the project to PyPI test instance.
make publish-live - publish the project to PyPI production.
make docs - run sphinx to create project documentation.


On Windows there is a make.cmd file that works in a similar way to the make command on Unix-like operating systems.

Before Submitting

Before contributing code please make sure you’ve read Contributing Code and follow the checklist for contributing changes.