Error Handling Overview
Input error management is crucial for creating robust and reliable Python applications that can gracefully handle unexpected user inputs.
graph TD
A[Input Errors] --> B[Type Conversion Errors]
A --> C[Range Validation Errors]
A --> D[Format Errors]
A --> E[Boundary Violation Errors]
Common Error Handling Techniques
Exception Handling Strategy
def validate_range_input(value, min_val, max_val):
"""
Comprehensive input validation method
Args:
value: User input
min_val: Minimum acceptable value
max_val: Maximum acceptable value
Raises:
ValueError: For invalid input types or range violations
"""
try:
## Convert input to numeric type
numeric_value = float(value)
## Check range boundaries
if numeric_value < min_val or numeric_value > max_val:
raise ValueError(f"Value must be between {min_val} and {max_val}")
return numeric_value
except ValueError as e:
print(f"Input Error: {e}")
return None
## Example usage
result = validate_range_input("42", 0, 100)
Error Handling Patterns
Error Type |
Handling Approach |
Example |
Type Error |
Type conversion check |
isinstance() validation |
Value Error |
Range boundary validation |
Minimum/maximum limits |
Conversion Error |
Safe type casting |
try-except blocks |
Advanced Error Management
Custom Error Classes
class RangeInputError(Exception):
"""
Custom exception for range input violations
"""
def __init__(self, message, value):
self.message = message
self.value = value
super().__init__(self.message)
def strict_range_validation(value, min_val, max_val):
try:
numeric_value = float(value)
if numeric_value < min_val or numeric_value > max_val:
raise RangeInputError(
f"Value {value} outside allowed range",
numeric_value
)
return numeric_value
except (ValueError, RangeInputError) as e:
print(f"Validation Error: {e}")
return None
Logging and Monitoring
Implementing Robust Error Logging
import logging
## Configure logging
logging.basicConfig(
level=logging.ERROR,
format='%(asctime)s - %(levelname)s: %(message)s'
)
def log_input_errors(func):
"""
Decorator for logging input errors
"""
def wrapper(*args, **kwargs):
try:
return func(*args, **kwargs)
except Exception as e:
logging.error(f"Input Error: {e}")
return None
return wrapper
Best Practices
- Use explicit error messages
- Implement comprehensive validation
- Provide user-friendly feedback
- Log errors for debugging
- Use type hints and docstrings
LabEx Recommendation
LabEx encourages developers to practice error handling techniques through interactive coding environments that simulate real-world input scenarios.
Key Takeaways
- Anticipate potential input errors
- Use multiple validation layers
- Provide clear error communication
- Implement graceful error recovery mechanisms