Python Naming Convention Rules

1. General

  • Avoid using names that are too general or too wordy. Strike a good balance between the two.
  • Bad: data_structure, my_list, info_map, dictionary_for_the_purpose_of_storing_data_representing_word_definitions
  • Good: user_profile, menu_options, word_definitions
  • Don’t be a jackass and name things “O”, “l”, or “I”
  • When using CamelCase names, capitalize all letters of an abbreviation (e.g. HTTPServer)

2. Packages

  • Package names should be all lower case
  • When multiple words are needed, an underscore should separate them
  • It is usually preferable to stick to 1 word names

3. Modules

  • Module names should be all lower case
  • When multiple words are needed, an underscore should separate them
  • It is usually preferable to stick to 1 word names

4. Classes

  • Class names should follow the UpperCaseCamelCase convention
  • Python’s built-in classes, however are typically lowercase words
  • Exception classes should end in “Error”

5. Global (module-level) Variables

  • Global variables should be all lowercase
  • Words in a global variable name should be separated by an underscore

6. Instance Variables

  • Instance variable names should be all lower case
  • Words in an instance variable name should be separated by an underscore
  • Non-public instance variables should begin with a single underscore
  • If an instance name needs to be mangled, two underscores may begin its name

7. Methods

  • Method names should be all lower case
  • Words in an method name should be separated by an underscore
  • Non-public method should begin with a single underscore
  • If a method name needs to be mangled, two underscores may begin its name

8. Method Arguments

  • Instance methods should have their first argument named ‘self’.
  • Class methods should have their first argument named ‘cls’

9. Functions

  • Function names should be all lower case
  • Words in a function name should be separated by an underscore

10. Constants

  • Constant names must be fully capitalized
  • Words in a constant name should be separated by an underscore