caaalle 2.0.0

caaalle

caaalle

Installing

Install and update using pip:

pip3 install caaalle

Project Dependencies

We use pipenv for managing project dependencies and Python environments (i.e. virtual environments). These dependencies are not to be confused with the package installation dependencies for the package under developement - i.e. those that need to be defined in the install_requires section of setup.py. All of the direct packages dependencies required to run the project's code (e.g. NumPy for tensors), as well as all the packages used during development (e.g. flake8 for code linting and IPython for interactive console sessions), are described in the Pipfile. Their precise downstream dependencies are crystallised in Pipfile.lock, which is used to guarentee repeatable (i.e. deterministic) builds.

Installing Pipenv

To get started with Pipenv, first of all download it - assuming that there is a 'global' version of Python available on your system and on the PATH, then this can be achieved by running the following command,

pip3 install pipenv

For more information, including advanced configuration options, see the official pipenv documentation.

Installing this Projects' Dependencies

Make sure that you're in the project's root directory (the same one in which Pipfile resides), and then run,

pipenv install --dev

This will install all of the direct project dependencies as well as the development dependencies (the latter a consequence of the --dev flag). To add and remove dependencies as required for your new project, use pipenv install and pipenv uninstall as required, using the --dev flag for development-only dependencies.

Running Python and IPython from the Project's Virtual Environment

In order to open a Python REPL using within an environment that precisely mimics the one the project is being developed with, use Pipenv from the command line as follows,

pipenv run python3

The python3 command could just as well be ipython3.

Running Unit Tests

All test have been written using the PyTest package. Tests are kept in the tests folder and can be run from the command line by - e.g. by invoking,

pipenv run pytest

The test suite is structured as an independent Python package as follows:

tests/
 |   __init__.py
 |   conftest.py
 |   test_caaalle.py

The conftest.py module is used by PyTest - in this particular instance for loading test data and building objects that will then be used by potentially many other tests. These are referred to as 'fixtures' in PyTest - more details can be found here.

Linting Code

I prefer to use flake8 for style guide enforcement. This can be invoked from the command line by running,

pipenv run flake8 caaalle

Static Type Checking

We have used the Python type annotation framework, together with the MyPy package, to perform static type checks on the codebase. Analogous to any linter or unit testing framework, MyPy can be run from the command line as follows,

pipenv run python -m mypy caaalle/*.py

MyPy options for this project can be defined in the mypy.ini file that MyPy will look for by default. For more information on the full set of options, see the mypy documentation.

Examples of type annotation and type checking for library development can be found in the py_pkg.curves.py module. This should also be cross-referenced with the improvement to readability (and usability) that this has on package documentation.

Documentation

The documentation in the docs folder has been built using Sphinx. We have used the default 'quickstart' automatic configuration, which was originally triggered by executing,

pipenv run sphinx-quickstart

The output is based primarily on the Docstrings in the source code, using the autodoc extension within Sphinx (specified during the 'quickstart'). The contents for the entry point into the docs (index.html), is defined in the index.rst file, which itself imports the modules.rst file that lists all of the modules to document. The documentation can be built by running the following command,

pipenv run sphinx-build -b html docs/source docs/build_html

The resulting HTML documentation can be accessed by opening docs/build_html/index.html in a web browser.

My preferred third party theme from Read the Docs has also been used, by installing the sphinx_rtd_theme as a development dependency and modifying docs/source/config.py as follows:

import sphinx_rtd_theme
html_theme = "sphinx_rtd_theme"
html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]

Building Deployable Distributions

The recommended (and most pragmatic) way of deploy this package is to build a Python wheel and to then to install it in a fresh virtual environment on the target system. The exact build configuration is determined by the parameters in setup.py. Note, that this requires that all package dependencies also be specified in the install_requires declaration in setup.py, regardless of their entry in Pipfile. For more information on Python packaging refer to the Python Packaging User Guide and the accompanying sample project. To create the Python wheel run,

pipenv run python setup.py bdist_wheel

This will create build, caaalle.egg-info and dist directories - the wheel can be found in the latter. This needs to be copied to the target system (which we are assuming has Python and Pipenv available as a minimum), where it can be installed into a new virtual environment, together with all downstream dependencies, using,

pipenv install path/to/your-package.whl

Automated Testing and Deployment using Travis CI

We have chosen Travis for Continuous Integration (CI) as it integrates very easily with Python and GitHub (where I have granted it access to my public repositories). The configuration details are kept in the .travis.yaml file in the root directory:

ncsudo: required

language: python

python:
  - 3.7-dev

install:
  - pip install pipenv
  - pipenv install --dev

script:
  - pipenv run pytest

deploy:
  provider: pypi
  user: __token__
  password:
    secure: my-encrypted-pypi-password
  on:
    tags: true
  distributions: bdist_wheel