This documentation is for a development version. Click here for the latest stable release (v0.11.1).

Style guide

NengoBones attempts to enforce as much of this style guide as possible. However, since not everything can be automatically enforced, all Nengo developers should be familiar with this style guide and follow it when working on Nengo projects.


We use black for automated formatting. We recommend that you set up your editor to run black when you save a Python file; see Black editor integration for details on how to do that.

Whether you set up black with your editor or not, you should run black through a pre-commit hook. To do this, first install pre-commit. Then, run

pre-commit install

to install black and any other pre-commit hooks that a project is using.

We use flake8 and pylint for automated checks. The exact options may vary from project to project, so the easiest way to run these checks is to run the .ci/ script locally.

bones-generate --output-dir .ci ci-scripts && .ci/ script

If you are missing any required packages, running .ci/ install should install all requirements.

Class member order

In general, we stick to the following order for members of Python classes.

  1. Class-level member variables (e.g., nengo.Ensemble.probeable).

  2. Parameters (i.e., instances of nengo.params.Parameter) with the parameters in __init__ going first in that order, then parameters that don’t appear in __init__ in alphabetical order. All these parameters should appear in the Parameters section of the docstring in the same order.

  3. __init__

  4. Other special (__x__) methods in alphabetical order, except when a grouping is more natural (e.g., __getstate__ and __setstate__).

  5. @property properties in alphabetical order.

  6. @staticmethod methods in alphabetical order.

  7. @classmethod methods in alphabetical order.

  8. Methods in alphabetical order.

“Hidden” versions of the above (i.e., anything starting with an underscore) should either be placed right after they’re first used, or at the end of the class.


These are guidelines that should be used in general, not strict rules. If there is a good reason to group differently, then feel free to do so, but please explain your reasoning in a code comment or commit message.


We use numpydoc and NumPy’s guidelines for docstrings, as they are readable in plain text and when rendered with Sphinx.

We use the default role of obj in documentation, so any strings placed in backticks in docstrings will be cross-referenced properly if they unambiguously refer to something in the Nengo documentation. See Cross-referencing syntax and the Python domain for more information.


We use several advanced git features that rely on well-formed commit messages. Commit messages should fit the following template.

Capitalized, short (50 chars or less) summary

More detailed body text, if necessary.  Wrap it to around 72 characters.
The blank line separating the summary from the body is critical.

Paragraphs must be separated by a blank line.

- Bullet points are okay, too.
- Typically a hyphen or asterisk is used for the bullet, followed by
  single space, with blank lines before and after the list.
- Use a hanging indent if the bullet point is longer than a
  single line (like in this point).


JS, TS, CSS, HTML, etc