PEP 8 & Code Linting

PEP 8 is Python's official style guide. Linters (flake8, pylint) and formatters (black, autopep8) enforce consistent, readable code automatically.

10 min•By Priygop Team•Updated 2026

PEP 8 & Linting

# PEP 8 key rules:

# 1. Indentation: 4 spaces
def good_function():
    if True:
        print("4 spaces")

# 2. Line length: max 79 (or 120)
# 3. Blank lines: 2 before functions/classes, 1 between methods
# 4. Imports at the top, grouped:
#    stdlib → third-party → local

# 5. Naming conventions:
# variables/functions: snake_case
# classes: PascalCase
# constants: UPPER_SNAKE_CASE
# private: _leading_underscore

MAX_RETRIES = 3          # constant
user_name = "Alice"      # variable

class UserAccount:       # class
    def get_balance(self):  # method
        _internal = 42       # private
        return _internal

# 6. String quotes: consistent (either ' or ")
# 7. Trailing whitespace: none
# 8. Spaces around operators: yes

# Linting tools:
print("=== Linting Tools ===")
tools = {
    "flake8": "Style checker (PEP 8)",
    "pylint": "Comprehensive linter",
    "black": "Opinionated formatter",
    "isort": "Import sorter",
    "mypy": "Static type checker",
    "ruff": "Fast linter (Rust-based)",
}
for tool, desc in tools.items():
    print(f"  pip install {tool:8s}  # {desc}")

# Setup commands:
print("\n=== Usage ===")
print("  flake8 myfile.py     # check style")
print("  black myfile.py      # auto-format")
print("  mypy myfile.py       # check types")
print("  ruff check .         # fast lint all")

Tip

Set up Git hooks with pre-commit to run linting and tests before each commit. It catches issues early.

Diagram

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PEP 8 is Python's style guide - follow it and your code looks professional

Common Mistake

Warning

Skipping code review. Even your own code benefits from a second look. Use pull requests even on solo projects.

Quick Quiz

Practice Task

Note

(1) Install pre-commit hooks. (2) Set up a CI pipeline. (3) Add automated testing to your workflow.

Topics in This Module

PEP 8 & Linting

# PEP 8 key rules:

# 1. Indentation: 4 spaces
def good_function():
    if True:
        print("4 spaces")

# 2. Line length: max 79 (or 120)
# 3. Blank lines: 2 before functions/classes, 1 between methods
# 4. Imports at the top, grouped:
#    stdlib → third-party → local

# 5. Naming conventions:
# variables/functions: snake_case
# classes: PascalCase
# constants: UPPER_SNAKE_CASE
# private: _leading_underscore

MAX_RETRIES = 3          # constant
user_name = "Alice"      # variable

class UserAccount:       # class
    def get_balance(self):  # method
        _internal = 42       # private
        return _internal

# 6. String quotes: consistent (either ' or ")
# 7. Trailing whitespace: none
# 8. Spaces around operators: yes

# Linting tools:
print("=== Linting Tools ===")
tools = {
    "flake8": "Style checker (PEP 8)",
    "pylint": "Comprehensive linter",
    "black": "Opinionated formatter",
    "isort": "Import sorter",
    "mypy": "Static type checker",
    "ruff": "Fast linter (Rust-based)",
}
for tool, desc in tools.items():
    print(f"  pip install {tool:8s}  # {desc}")

# Setup commands:
print("\n=== Usage ===")
print("  flake8 myfile.py     # check style")
print("  black myfile.py      # auto-format")
print("  mypy myfile.py       # check types")
print("  ruff check .         # fast lint all")

Topics in This Module