WK2: Coding Standards and Hands-on Exercises (Session 2)

• Programming
• Higher Education (degree)

Welcome

Coding Standards and Hands-on Exercises

Module Lecturer: Dr Raghav Kovvuri

Email: [e-mail]

Week 2

Coding Standards Introduction

Definition: A set of guidelines for a specific programming language that recommend programming style, practices, and methods

Importance:

• Improves code readability
• Facilitates maintenance
• Helps prevent errors
• Promotes consistency across projects and teams

Python's primary coding standard: PEP 8 (Python Enhancement Proposal 8)

Tools for enforcement: pylint, flake8, black (auto-formatter)

PEP 8 - Key Guidelines (1)

Indentation:

• Use 4 spaces per indentation level

Maximum Line Length:

• Limit lines to 79 characters for code
• Limit docstrings/comments to 72 characters

Imports:

• One import per line
• Group imports: Standard Library, Third-Party, Local
• Avoid wildcard imports (from module import *)

PEP 8 - Key Guidelines (2)

Naming Conventions:

• Functions, variables, and attributes: lowercase_with_underscores
• Classes: CapitalizedWords
• Constants: ALL_CAPS
• Protected instance attributes: _single_leading_underscore
• Private instance attributes: __double_leading_underscore

Whitespace:

• Surround top-level functions and classes with two blank lines
• Use blank lines sparingly inside functions to indicate logical sections

PEP 8 - Key Guidelines (3)

Comments:

• Use complete sentences, starting with a capital letter
• Use inline comments sparingly
• Update comments when code changes

Documentation Strings:

• Enclose in triple quotes: """
• First line should be a summary
• Multi-line docstrings: summary line, blank line, details

Hands-on Exercise 1

Code Refactoring:

Task: Refactor the code given (download from Canvas) to adhere to PEP 8 standards

Key points to address:

• Function naming
• Whitespace in expressions
• Docstrings
• Line breaks and indentation

Hands-on Exercise 2

Task: Create a simple to-do list program that demonstrates good coding practices and adherence to PEP 8.

Requirements:

1) Use a list to store to-do items

2) Implement functions for:

• Adding an item
• Removing an item
• Displaying the list

3) Use a main loop for user interaction

4) Include appropriate comments and docstrings

5) Follow PEP 8 guidelines for naming and formatting

Best Practices for Clean Code

1) DRY (Don't Repeat Yourself)

• Avoid duplicating code; use functions or loops instead

2) KISS (Keep It Simple, Stupid)

• Write simple, straightforward code
• Avoid unnecessary complexity

3) YAGNI (You Aren't Gonna Need It)

• Don't add functionality until it's necessary

4) Single Responsibility Principle

• Each function or class should have one, well-defined purpose

5) Meaningful Names

• Choose descriptive names for variables, functions, and classes

6) Error Handling

• Use try-except blocks to handle exceptions gracefully

7) Code Organization:

• Group related code together
• Use modules to separate concerns

Tools for Maintaining Code Quality

Linters:

• pylint: Checks for errors and enforces a coding standard
• flake8: Combines PyFlakes, pycodestyle, and Ned Batchelder's McCabe script

Formatters:

• black: An opinionated code formatter; "any style guide is better than no style guide"
• YAPF: Formatter from Google, highly configurable

Type Checkers:

• mypy: Optional static type checker for Python

Documentation Generators:

• Sphinx: Generates documentation from Python docstrings
• pdoc: Auto-generates API documentation for Python modules

Testing Frameworks:

• unittest: Built-in unit testing framework
• pytest: More feature-rich testing framework

Recap and next session

Further Practice:

1) Refactor previous exercises to follow PEP 8

2) Use pylint or flake8 to check your code

3) Try using black to automatically format your code

4) Start a small project, focusing on clean code from the beginning

Next Session Preview:

• Introduction to Object-Oriented Programming
• How OOP principles can further improve code organization and reusability