Day 29 - Debugging

Author: Zemerik

Day 29 - Debugging/Commands.mdx

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+```sh
+pdb Commands:
+  n(ext)      - Execute next line
+  s(tep)      - Step into function
+  r(eturn)    - Run until function returns
+  c(ontinue)  - Continue execution
+  l(ist)      - Show current code context
+  p <var>     - Print variable value
+  q(uit)      - Quit debugger
+
+Logging Levels:
+  DEBUG    - Detailed information
+  INFO     - Confirmation of operation
+  WARNING  - Potential issues
+  ERROR    - Serious problems
+  CRITICAL - Fatal errors
+```

Day 29 - Debugging/README.md

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+# Day 29: Debugging
+
+## What You'll Learn:
+- Using Python Debugger (pdb)
+- Setting breakpoints and stepping through code
+- Configuring logging module
+- Logging levels and handlers
+- Crash investigation techniques
+
+## Files:
+1. `pdb_example.py` - Debugger usage
+2. `logging_config.py` - Logging setup
+3. `advanced_debugging.py` - Post-mortem debugging
+4. `error_handling.py` - Structured logging
+
+## Exercises:
+1. Debug a faulty function that:
+   - Miscalculates factorial values
+   - Fails on specific inputs
+   - Use pdb to identify logic errors
+
+2. Implement logging in a file processor:
+   - Track file operations with different log levels
+   - Capture exceptions with tracebacks
+   - Rotate logs when they reach 1MB

Day 29 - Debugging/advanced_debugging.py

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+import pdb
+
+def analyze_data(data):
+    # Post-mortem debugging
+    results = []
+    for item in data:
+        pdb.set_trace()
+        if item < 0:  # Break when negative values appear
+            results.append(0)
+        else:
+            results.append(item * 2)
+    return results
+
+# Test with problematic data
+data = [1, 3, -5, 8]
+analyze_data(data)

Day 29 - Debugging/error_handling.py

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+import logging
+from logging.handlers import RotatingFileHandler
+
+logger = logging.getLogger("data_processor")
+logger.setLevel(logging.DEBUG)
+
+handler = RotatingFileHandler(
+    "data.log",
+    maxBytes=1024*1024,  # 1MB
+    backupCount=3
+)
+formatter = logging.Formatter(
+    "%(asctime)s - %(levelname)s - %(message)s"
+)
+handler.setFormatter(formatter)
+logger.addHandler(handler)
+
+def process_record(record):
+    try:
+        logger.debug(f"Processing: {record}")
+        if not record.is_valid():
+            logger.warning("Invalid record format")
+        # Processing logic here
+    except Exception as e:
+        logger.error(f"Failed to process record: {str(e)}", exc_info=True)

Day 29 - Debugging/logging_config.py

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+import logging
+from pathlib import Path
+
+# Create logs directory
+Path("logs").mkdir(exist_ok=True)
+
+# Configure root logger
+logging.basicConfig(
+    level=logging.DEBUG,
+    format="%(asctime)s - %(name)s - %(levelname)s - %(message)s",
+    handlers=[
+        logging.FileHandler("logs/app.log"),
+        logging.StreamHandler()
+    ]
+)
+
+logger = logging.getLogger(__name__)
+
+def main():
+    logger.info("Application started")
+    try:
+        1 / 0
+    except Exception:
+        logger.exception("Critical error occurred")
+
+if __name__ == "__main__":
+    main()

Day 29 - Debugging/pdf_example.py

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+import pdb
+
+def calculate_discount(price, discount):
+    pdb.set_trace()  # Breakpoint
+    if discount > 0.5:
+        print("Warning: Large discount applied")
+    return price - (price * discount)
+
+# Debug this calculation
+print(calculate_discount(100, 0.6))