Building programs with Python

Python Style Guide

Learning Objectives

• Python coding conventions

This is taken from PEP-008: Python Style Guide. It is a semi-official guide to Python coding conventions.

We should stick to this unless we have hard data that proves something else is better.

Basic layout is as below:

• Indent blocks using four spaces
• Keep lines less than 80 characters long
• Separate functions with two blank lines
• Separate logical chunks of long functions with a single blank line
• Put comments on lines of their own, rather than to the right of code

Here are some basic python style rules listed in a table below:

Rule	Good	Bad
No whitespace immediately inside parentheses or before the parenthesis starting indexing or slicing	max(candidates[sublist])	max( candidates[ sublist ] ) , max (candidates [sublist] )
No whitespace immediately before comma or colon	if limit > 0: print minimum, limit	if limit > 0 : print minimum , limit
Use space around arithmetic and in-place operators	x += 3 * 5	x+=3*5
No spaces when specifying default parameter values	def integrate(func, start=0.0, interval=1.0)	def integrate(func, start = 0.0, interval = 1.0)
Never use names that are distinguished only by "l", "1", "0", or "O"	tempo_long and tempo_init	tempo_l and tempo_1
Short lower-case names for modules (i.e., files)	geology	Geology or geology_package
Upper case with underscores for constants	TOLERANCE or MAX_AREA	Tolerance or MaxArea
Camel case for class names	SingleVariableIntegrator	single_variable_integrator
Lowercase with underscores for function and method names	divide_region	divRegion
and member variables	max_so_far	maxSoFar
Use is and is not when comparing to special values	if current is not None:	if current != None:
Use isinstance when checking types	if isinstance(current, Rock):	if type(current) == Rock:

Table 8.1: Basic Python Style Rules