python / python-functions
25 mins
Python Level 10: Building Command-Line Tools
Why This Matters: Constructing modular Python CLI tools with sys.argv parameters.
## Production Python Scripting
Constructing modular command-line scripts.
```python
import sys
def main():
target = sys.argv[1] if len(sys.argv) > 1 else "default.txt"
print(f"Processing: {target}")
if __name__ == "__main__":
main()
```
MENTAL MODEL & MEMORY LAYOUT
CLI SCRIPT FLOW: sys.argv ──► Reads terminal arguments ──► Invokes main() ──► Produces output report
COMMON PITFALLS TO AVOID
- Omitting `if __name__ == '__main__':` block, causing main script to execute upon import.
Modular CLI Utility Function
def build_report(title, metrics):
return f"=== {title.upper()} ===\n" + "\n".join([f"{k}: {v}" for k, v in metrics.items()])
print(build_report("Daily Stats", {"Users": 120, "Errors": 0}))Generates formatted multi-line CLI text report from metrics dictionary.
CONCEPT MASTERY CHECKPOINT
Why is `if __name__ == '__main__':` used in Python scripts?
NEXT RECOMMENDED LESSON
DSA Module 1: Big-O Time & Space Complexity
Challenge: Format dictionary into key-value string report.