Python naming standards for Beginners

Cheat sheet covers print, concatenation, list, tuples, if-elif-else statements, dictionaries, user input, while loops, classes, files I/O, functions, exceptions etc..

1. Variables

• Use snake_case for variable names: words are lowercase and separated by underscores.
• Avoid single-letter names except in loops or temporary, throwaway variables.

student_name = "Alice"
total_score = 95

2. Functions

• Use snake_case for function names.
• Name functions based on their purpose, using descriptive verbs or phrases.

def calculate_area(radius):
return 3.14 * radius ** 2

3. Constants

• Use ALL_CAPS for constants, with words separated by underscores.
• Place constants at the beginning of a file or module.

PI = 3.14159
MAX_CONNECTIONS = 100

4. Classes

• Use PascalCase (capitalize each word without underscores).
• Class names should be nouns that describe objects.

class Circle:
pass

5. Modules and Packages

• Use lowercase for module and package names.
• Use underscores sparingly in module names (e.g., my_module), and avoid them in package names unless needed for clarity.

my_module.py

6. Instance and Class Attributes

• Use snake_case for attribute names.
• Private attributes (for internal use only) should start with a single underscore (_), while strongly private attributes (meant to prevent subclass access) start with two underscores (__).

class Rectangle:
def __init__(self, width, height):
self.width = width
self.height = height
self._area_cache = None

7. Method Names

• Use snake_case for method names.
• Follow the same rules as functions, but methods inside a class often relate specifically to that class’s behavior.

class Shape:
def calculate_area(self):
pass

8. Naming Conventions for Special Methods

• Special methods that start and end with double underscores are known as “dunder” (double underscore) methods, like __init__ for initialization.
• These should be used as-is and never modified for regular functions.

class Person:
def __init__(self, name):
self.name = name

9. Avoid Reserved Words

• Python has reserved words that cannot be used as identifiers (e.g., class, def, if, else, etc.).

# Avoid using reserved keywords
class_ = "Math" # Instead of class