Developer’s Guide

This page is for those of you who enjoy diving into guidelines, coding conventions, and project philosophies. If you’re looking to get started more quickly, instead check out the Contributing and Writing Drivers pages.

The Instrumental Manifesto

A major goal of Instrumental is to try to unify and simplify a lot of common, useful operations. Essential to that is a consistent and coherent interface.

  • Simple, common tasks should be simple to perform

  • Options should be provided to enable more complex tasks

  • Documentation is essential

  • Use of physical units should be standard and widespread

Simple, common tasks should be simple to perform

Tasks that are conceptually simple or commonly performed should be made easy. This means having sane defaults.

Options should be provided to enable more complex tasks

Along with sane defaults, provide options. Typically, this means providing optional parameters in functions and methods.

Documentation is essential

Providing Documentation can be tiring or boring, but, without it, your carefully crafted interfaces can be opaque to others (including future-you). In particular, all functions and methods should have brief summary sentences, detailed explanations, and descriptions of their parameters and return values.

This also includes providing useful error messages and warnings that the average user can actually understand and do something with.

Use of physical units should be standard and widespread

Units in scientific code can be a big issue. Instrumental incorporates unitful quantities using the very nice Pint package. While units are great, it can seem like extra work to start using them. Instrumental strives to use units everywhere to encourage their widespread use.

Coding Conventions

As with most Python projects, you should be keeping in mind the style suggestions in PEP8. In particular:

  • Use 4 spaces per indent (not tabs!)

  • Classes should be named using CapWords capitalization

  • Functions and methods should be named using lower_case_with_underscores

    • As an exception, python wrapper (e.g. cffi/ctypes) code used as a _thin_ wrapper to an underlying library may stick with its naming convention for functions/methods. (See the docs for Attocube stages for an example of this)

  • Modules and packages should have short, all-lowercase names, e.g. drivers

  • Use a _leading_underscore for non-public functions, methods, variables, etc.

  • Module-level constants are written in ALL_CAPS

Strongly consider using a plugin for your text editor (e.g. vim-flake8) to check your PEP8 compliance.

It is OK to have lines over 80 characters, though they should almost always be 100 characters or less.

Docstrings

Code in Instrumental is primarily documented using python docstrings, following the numpydoc conventions. In general, you should also follow the guidelines of pep 257.

  • No spaces after the opening triple-quote

  • One-line docstrings should be on a single line, e.g. """Does good stuff."""

  • Multi-liners have a summary line, followed by a blank line, followed by the rest of the doc. The closing quote should be on its own line

Python 2/3 Compatibility

Instrumental was originally developed for Python 2.7 and long maintained Python 2/3 cross compatibility. As of release 0.7, we haved dropped that support and now require Python 3.7+. This means all future development should target Python 3.

Python 2 support may be removed from existing code as a part of future development, though this is not currently a priority.

Developing Drivers

If you’re considering writing a driver, thank you! Check out Writing Drivers for details.