Streamlining Error Handling with Custom Exceptions in Python

{
  "title": "Streamlining Error Handling with Custom Exceptions in Python",
  "description": "Learn how to define and use custom exceptions in your Python code to create clearer and more efficient error handling strategies.",
  "category": "Python Cursor Rules",
  "rules": [
    {
      "name": "Define Custom Exceptions",
      "description": "Create custom exception classes by inheriting from Python's built-in Exception class to represent specific error conditions in your application.",
      "example": "class InvalidInputError(Exception):\n    \"\"\"Exception raised for invalid input.\"\"\"\n    pass"
    },
    {
      "name": "Use Descriptive Names",
      "description": "Name your custom exceptions with descriptive and meaningful names that clearly convey the nature of the error.",
      "example": "class OutOfStockError(Exception):\n    \"\"\"Exception raised when a product is out of stock.\"\"\"\n    pass"
    },
    {
      "name": "Provide Informative Messages",
      "description": "Include informative error messages in your custom exceptions to aid in debugging and provide context about the error.",
      "example": "class InvalidUserInputError(Exception):\n    def __init__(self, message):\n        super().__init__(message)"
    },
    {
      "name": "Create Exception Hierarchies",
      "description": "Organize custom exceptions into a hierarchy by creating base exception classes for related errors, allowing for more granular error handling.",
      "example": "class ApplicationError(Exception):\n    \"\"\"Base class for application-specific exceptions.\"\"\"\n    pass\n\nclass DatabaseError(ApplicationError):\n    \"\"\"Exception raised for database-related errors.\"\"\"\n    pass\n\nclass NetworkError(ApplicationError):\n    \"\"\"Exception raised for network-related errors.\"\"\"\n    pass"
    },
    {
      "name": "Document Custom Exceptions",
      "description": "Provide clear documentation for your custom exceptions, including their purpose and when they should be raised, to assist other developers in understanding and using them appropriately.",
      "example": "class InvalidUserInputError(Exception):\n    \"\"\"Exception raised for invalid user input.\n\n    Attributes:\n        message -- explanation of the error\n    \"\"\"\n    def __init__(self, message):\n        super().__init__(message)"
    },
    {
      "name": "Avoid Overusing Custom Exceptions",
      "description": "Use custom exceptions judiciously; reserve them for cases where built-in exceptions do not suffice, to prevent unnecessary complexity in your codebase.",
      "example": "class InvalidUserInputError(ValueError):\n    \"\"\"Exception raised for invalid user input.\"\"\"\n    pass"
    },
    {
      "name": "Test Exception Handling",
      "description": "Thoroughly test your exception handling code to ensure that custom exceptions are raised and handled correctly, and that they provide the intended information.",
      "example": "import unittest\n\nclass TestCustomExceptions(unittest.TestCase):\n    def test_invalid_user_input_error(self):\n        with self.assertRaises(InvalidUserInputError) as context:\n            raise InvalidUserInputError(\"Invalid input\")\n        self.assertEqual(str(context.exception), \"Invalid input\")\n\nif __name__ == \"__main__\":\n    unittest.main()"
    }
  ]
}