Aug 26: PEP 8 Style Guide, flake8

Learning Objectives

After today's class, you should be able to:

• Explain what a PEP is and why PEPs are important.
• Run flake8 to check your code before submitting.
• Describe at least three style guidelines for Python.

Mini Lecture

Announcements [10 min]

• See the Help page:
  • TA Hours (Sun–Thu) and Office Hours (Mon–Fri)
  • Ask and answer questions on Piazza (anytime)
• Due tomorrow
  • Ch 1 on zyBooks (orange required, blue optional)
  • HW 1 on Gradescope
• Due Wednesday
  • Syllabus Quiz on Canvas (must get 5/5 = 100%)
  • HW1 Reflection on Canvas

Python Style Guide [10 min]

• PEP = Python Enhancement Proposal
  • PEP 8 – Style Guide for Python Code
    • Prettier version: https://pep8.org/
  • PEP 257 – Docstring Conventions
    • Real-world example: Google's style guide
• Check your code before submitting to Gradescope!
  • Installing Thonny, flake8
  • Docstring Requirements

Mini Exercise

Fixing Style [20 min]

• Download payroll.py and setup.cfg
• Run payroll.py first to see how it works
• Run !flake8 payroll.py in the shell
  • You should see several lines of output
  • payroll.py:4:18 means "Line 4, Char 18"
• Correct each issue, one by one, in the editor
  • Rerun flake8 by pressing Up+Enter in the shell
• If you finish early, delete setup.cfg and go all the way PEP 8
  • Our config does not enforce all of PEP 8's requirements

Thonny Tips

Quick Demo [10 min]

• Have you discovered the View menu in Thonny?
  • Consider showing "Files" and "Variables"
  • Other windows might be useful to you
• Tools > Options… Theme & Font
  • UI theme: Clean Dark
  • Syntax theme: Tomorrow Night Eighties
  • Feel free to choose the ones you want!