Python Level 6: Context Managers & Exception Blocks

Why This Matters: `with open()` context managers automatically cleanup resources even if errors occur.

## Safe Resource Management with Context Managers

Python uses `with open()` context managers to safely handle file streams.

```python
with open("data.txt", "w") as f:
    f.write("GrowCode Python Data Stream
")
# File closed automatically here!

try:
    val = int("abc")
except ValueError as e:
    print(f"Handled error: {e}")
```

MENTAL MODEL & MEMORY LAYOUT

CONTEXT MANAGER LIFECYCLE:
[ __enter__ Open File ] ──► [ Execute Block ] ──► [ __exit__ Auto Close File ]

COMMON PITFALLS TO AVOID

Forgetting context manager `with open(...)` and leaving unclosed file streams open.

Safe Integer Parsing Pattern

def safe_parse(s):
    try:
        return int(s)
    except ValueError:
        return 0
print(safe_parse("123")) # 123
print(safe_parse("invalid")) # 0

Handles parsing exceptions gracefully with try/except fallback.

CONCEPT MASTERY CHECKPOINT

Why is `with open(...)` preferred over raw `open()` and `close()` in Python?

NEXT RECOMMENDED LESSON

Python Level 7: OOP & Classes

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Challenge: Write function `safe_int(s)` returning int(s) if valid else 0.

Python Level 6: Context Managers & Exception Blocks

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