Naming Conventions
This lesson gets you familiarized with naming conventions used in Python.
The naming conventions of Python’s library are a bit of a mess, so we’ll never get this completely consistent – nevertheless, here are the currently recommended naming standards. New modules and packages (including third-party frameworks) should be written to these standards, but where an existing library has a different style, internal consistency is preferred.
Overriding Principle
Names that are visible to the user as public parts of the API should follow conventions that reflect usage rather than implementation.
Descriptive: Naming Styles
There are a lot of different naming styles. It helps to be able to recognize what naming style is being used, independently from what they are used for.
The following are the recommended ones:
- lower_case_with_underscores
- UPPER_CASE_WITH_UNDERSCORES
Names to Avoid
Never use the characters ‘l’ (lowercase letter el), ‘O’ (uppercase letter oh), or ‘I’ (uppercase letter eye) as single character variable names.
In some fonts, these characters are indistinguishable from the numerals one and zero. When tempted to use ‘l’, use ‘L’ instead.
Class Names
Class names should normally use the CapWords convention.
The naming convention for functions may be used instead in cases where the interface is documented and used primarily as a callable.
Note that there is a separate convention for builtin names: most builtin names are single words (or two words run together), with the CapWords convention used only for exception names and builtin constants.
Function and Variable Names
Always use self for the first argument to instance methods.
Always use cls for the first argument to class methods.
If a function argument’s name clashes with a reserved keyword, it is generally better to append a single trailing underscore rather than use an abbreviation or spelling corruption. Thus class_ is better than clss. (Perhaps better is to avoid such clashes by using a synonym.)
Constants
Constants are usually defined on a module level and written in all capital letters with underscores separating words. Examples include MAX_OVERFLOW and TOTAL.