CONTRIBUTE.md

Contribute

Please read this entire document before contributing any code.

Python

On your development computer:

• Use the very latest Anaconda release (conda update conda anaconda).
• Use a special phy conda environment based on the latest Python 3.x (3.4 at the time of writing).
• Have another phy2 clone environment based on Python 2.7.
• phy only supports Python 2.7, and Python 3.4+.
• Use six for writing compatible code (see the documentation here)
• You need the following dependencies for development (not required for using phy): pytest, pip, flake8, coverage, coveralls.
• For IPython, use the IPython git master branch (or version 3.0 when it will be released in early 2015).

A few rules:

• Every module phy/mypackage/mymodule.py must come with a phy/mypackage/tests/test_mymodule.py test module that contains a bunch of test_*() functions.
• Never import test modules in the main code.
• Do not import packages from phy/__init__.py. Every subpackage phy.stuff will need to be imported explicitly by the user. Dependencies required by this subpackage will only be loaded when the subpackage is loaded. This ensures that users can use phy.subpackageA without having to install the dependencies required by phy.subpackageB.
• phy's required dependencies are: numpy. Every subpackage can come with further dependencies. For example, phy.io.kwik depends on h5py.
• You can experiment with ideas and prototypes in the kwikteam/experimental repo. Use a different folder for every experiment.
• kwikteam/phy will only contain a master branch and release tags. There should be no experimental/debugging code in the entire repository.

GitHub flow

• Work through PRs from yourfork/specialbranch against phy/master exclusively.
• Set upstream to kwikteam/phy and origin to your fork.
• When master and your PR's branch are out of sync, rebase your branch in your fork.
• Two-pairs-of-eyes rule: every line of code needs to be reviewed by 2 people, including the author.
• Never merge your own PR to the main phy repository, unless in exceptional circumstances.
• A PR is assumed to be not ready for merge unless explicitly stated otherwise.
• Always run make test before stating that a PR is ready to merge (and ideally before pushing on your PR's branch).
• We try to have a code coverage close to 100%: always test all features you implement, and verify through code coverage that all lines are covered by your tests.
• Always wait for Travis to be green before merging.
• phy/master should always be stable and deployable.
• Use semantic versioning for stable releases.
• Do not make too many releases until the software is mature enough. Early adopters can work directly off master.
• We follow almost all PEP8 rules, except for a few exceptions.

Git commit messages

• Many small commits are better than few huge commits: there must be exactly one logical change per commit. Do not mix up whitespace changes with functional code changes; do not put two unrelated changes, or different functional changes, into a single commit. It is easy to revert and cherry-pick individual commits, but splitting up commits post-hoc is much harder.
• Follow the "50/72 rule". This means your commit messages must be in the following format:
  • First line: a brief summary of the change, no more than 50 characters (the "subject line"). Example: Added support for sparse arrays in loader
  • If the first line does not contain all the information needed, the second line must be blank.
  • Third (and following) lines: a more descriptive "body" of the commit. No more than 72 characters per line.
• More detail can be found here.

Text editor

Make sure your text editor is configured to:

• automatically clean blank lines (i.e. no lines containing only whitespace)
• use four spaces per indent level, and never tab indents
• enforce an empty blank line at the end of every text file
• display a vertical ruler at 79 characters (length limit of every line)

Below is a settings script for the popular text editor Sublime which you can put into your Preferences -> Settings (User):

{
    "auto_match_enabled": false,
    "detect_indentation": false,
    "ensure_newline_at_eof_on_save": true,
    "font_size": 14,
    "indent_to_bracket": true,
    "rulers":
    [
        79,
        99,
        119
    ],
    "tab_size": 4,
    "translate_tabs_to_spaces": true,
    "trim_trailing_white_space_on_save": true,
    "word_wrap": true,
    "wrap_width": 80
}