How to Effectively Raise and Handle Exceptions in Python?

Raising Exceptions in Python

Raising an Exception Manually

To purposefully raise an exception in Python, use the appropriate Exception constructor, ensuring specificity and providing a clear error message. For instance:

Best Practices

• Raise Specific Exceptions: Avoid raising generic Exception classes. Instead, opt for the most specific subclass that accurately describes the error.
• Provide Clear Message: Include a descriptive error message in the exception instance.
• Use raise in except Clause: If re-raising an exception within an except clause, use a bare raise statement to preserve the stack trace.

Don't Modify Errors Directly

Preserving stack traces when modifying errors is error-prone and compatibility issues can arise between Python versions. Instead, use Exception chaining (Python 3 only):

or, alternatively, sys.exc_info() (not recommended):

Creating Custom Error Types

When a specific error is not covered by existing exceptions, create custom error types by subclassing appropriate exceptions, such as LookupError. For example:

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