Python Style Guide

CS 303e - Python Style Guide

Code Layout

Indentation: Use 4 spaces per indentation level, or some consistent number of spaces. Two spaces is probably not enough, more than 6 is probably too many.
Tabs or Spaces: Never, ever, mix tabs and spaces.
Limit lines to 79 characters. This avoids line wrapping. Use a line continuation character if necessary.
Blank lines: Use blank lines before and after a function definition, and to separate segments of code. Blank lines should be used to increase readability of your code. Do not separate every two statements by a blank line.
Whitespace:

In a function call, do not separate the function name and its argument list by whitespace:

Use a blank space before and after the = sign in an assignment statement: i = i+1
Do not include multiple statements on the same line. This reduces readability.
Separate an in-line comment from the statement by at least 2 blank spaces:

Import Statements

        DO THIS:
            import os
            import sys
        NOT THIS:
            import sys, os

Comments

Use a couple of comments before a function or module to briefly describe what the function (or module) does. Likewise, before a chunk of related statements, include comments that describe briefly what the chunk does.
Don't use too many in-line comments. If you feel a need for them, you probably aren't using enough comments at the beginning of functions and complicated code segments.

Naming Conventions

We will use different naming styles, depending on what we are naming - a variable, a function, a class. We will talk more about these in class - use the convention that we discuss in lecture. There are some common naming conventions:

concatenated nouns, in which the first noun starts with a lowercase letter, and the other nouns start with an uppercase letter

Identifiers that use this convention: myLastName, myFavoriteHorrorMovie, firstNumber

Use meaningful names. Except for a loop index, it's rarely a good idea to have a variable i or a variable x. An identifier's name should give the reader a clue about what it represents.