README.md

Errors, Files, and Modules

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This section begins the transition from small in-memory programs to programs that must cope with failures, persistent data, and code organized across files.

Phase 7 starts with exception handling, then moves into deliberately raising exceptions, working safely with files and structured text data, and finally organizing Python code with imports, modules, and packages.

Learning path

Chapter	Main focus	Level	Status
01. try, except, else, and finally	Handle expected runtime failures while keeping normal and cleanup paths explicit	Beginner to intermediate	Available
02. Raising and Custom Exceptions	Signal invalid states deliberately with raise, re-raise or chain failures deliberately, and introduce simple custom exceptions	Intermediate	Available
03. open() and with	Read and write text files while managing resources safely	Beginner to intermediate	Planned
04. TXT, CSV, and JSON	Work with common text-based data formats and their boundaries	Intermediate	Planned
05. Imports, Modules, and Packages	Split code into reusable files and understand Python's import model	Intermediate	Planned

Prerequisite guidance

Before starting this phase, learners should be comfortable with:

• conditions and Boolean logic;
• loops;
• functions, parameters, and return values;
• basic type conversion;
• reading simple tracebacks conceptually;
• the difference between source-code comments and runtime behavior.

The complete beginner path through Phases 1–6 provides all of these foundations.

Recommended sequence

Study the chapters in numerical order when following the complete curriculum:

01. Handle exceptions
        ↓
02. Raise exceptions deliberately
        ↓
03. Open and manage files
        ↓
04. Read and write common data formats
        ↓
05. Organize code with modules and packages

The sequence is intentional. Before a program starts depending on files and multiple modules, it should have a clear model for what happens when an operation cannot complete normally.

Section goals

By the end of Phase 7, you should be able to:

• distinguish normal control flow from exception-driven control flow;
• handle specific runtime exceptions without hiding unrelated failures;
• use else and finally deliberately;
• raise appropriate exceptions when a function cannot honor its contract;
• open, read, and write files using safe resource-management patterns;
• work with plain text, CSV, and JSON at a beginner-friendly level;
• separate parsing, validation, transformation, and persistence responsibilities;
• import code from modules and packages;
• explain how files, exceptions, functions, and modules connect in a small real program.

Current chapter

Continue with Raising and Custom Exceptions.

Chapter 01 establishes handling exceptions that already occur. Chapter 02 adds deliberate raise, choosing built-in versus custom exception types, bare re-raising, explicit exception chaining, and the distinction between raise and assert. The next planned chapter is open() and with.

Directory structure

errors-files-and-modules/
├── README.md
├── README.pt-BR.md
├── README.es.md
├── 01-try-except-else-finally/
│   ├── README.md
│   ├── README.pt-BR.md
│   ├── README.es.md
│   └── examples/
│       ├── parse_integer.py
│       ├── safe_divide.py
│       └── trace_try_else_finally.py
└── 02-raise-and-custom-exceptions/
    ├── README.md
    ├── README.pt-BR.md
    ├── README.es.md
    └── examples/
        ├── custom_exception.py
        ├── exception_chaining.py
        └── validate_score.py

Planned chapter directories are added only when their content is actually published.