Scope and Lifetime Basics (Python)

This module practices variable lifetime in blocks and safe accumulation patterns.

Learning Metadata

• Difficulty: Beginner.
• Estimated Time: 20-35 minutes.
• Prerequisites: 01-foundations/functions, 01-foundations/control-flow.
• Cross-Language Lens: Compare block scope everywhere, then contrast deterministic destruction in C++ with garbage-collected lifetime in the other tracks.

Learning Outcomes

• FND-SCP-01: Predict name visibility across nested scopes.
• FND-SCP-02: Explain when values and resources cease to be usable.

Quick Run

Run from the repository root:

python scripts/automation.py run-module --module-path languages/python/01-foundations/scope-and-lifetime-basics

Topics Covered

• Variables declared in branches and loops.
• Accumulator patterns scoped to full function lifetime.
• Conditional assignment before use.
• Guard clauses for invalid ranges.

Common Pitfalls

• Using values before they are assigned in all branches.
• Declaring accumulators inside loops by mistake.
• Skipping range validation for score or count inputs.

Cross-Language Notes

• In Python, read this module through the native focus ?Scope and Lifetime Basics?; the shared folder name remains stable for side-by-side navigation.
• Use dynamic values, collection protocols, and context managers to demonstrate how to predict name visibility across nested scopes.
• Compare observable behavior with the other tracks when learning to explain when values and resources cease to be usable; equivalent evidence matters more than identical syntax.

Exercise Focus

• exercises/01.py: map numeric score ranges to a letter grade using branch-local logic.
• exercises/02.py: accumulate N integers and compute sum and average from shared state.

Exercise Specs

1. exercises/01.py

• Input: integer score expected in the range 0..100.
• Output: single letter grade from A to F.
• Edge cases: scores below 0 or above 100; exact boundary values 60/70/80/90.

2. exercises/02.py

• Input: positive count and then count integer values.
• Output: sum and average values.
• Edge cases: count <= 0; negative numbers within the sequence.

Check Your Work

Run from the repository root after implementing a starter:

python scripts/automation.py check-exercise --language python --level 01-foundations --module scope-and-lifetime-basics --exercise 01

Change --exercise 01 to --exercise 02 for the second task. Consult exercises/solutions/ only after making a complete attempt.

Checkpoint

• I can explain the core ideas of this module.
• I can run and modify example/main.py.
• I completed exercises/01.py.
• I completed exercises/02.py.
• I validated at least one edge case for each exercise.

Content revision 1d0b3f4