Chapter 24: Exception Handling
Errors happen in every program. Files go missing, users enter invalid data, networks fail. The difference between a program that crashes and one that handles errors gracefully is exception handling.
This chapter teaches you how to anticipate errors, handle them elegantly, and provide helpful feedback to users when things go wrong. You'll move from understanding what exceptions are and why they matter, through hands-on skills like catching and raising exceptions, to building a capstone project—a robust CSV file parser that handles real-world error scenarios professionally.
This chapter applies the AI-Native Learning methodology: you describe what error handling you want, explore exception patterns with your AI companion (Claude Code or Gemini CLI), validate your understanding through working code, and learn from errors by asking "why did this fail?"
🎯 Before You Begin
What You'll Learn
By the end of this chapter, you will be able to:
- Catch exceptions using try/except blocks and handle common error types
- Control exception flow with try/except/else/finally for complete error handling
- Raise exceptions intentionally and create custom exception classes for validation
- Apply error handling strategies like retry logic, fallback values, and graceful degradation
- Build robust programs that integrate all exception handling concepts in realistic projects (Capstone)