You've learned what exceptions are, how to catch them, raise them, and create child exceptions through inheritance. If that sounds like you're playing a farming simulator computer game, then you might want to consider taking your next holiday on a farm. You know, one of those where they still catch and raise real chickens that make baby chicks through inheritance and... I'm digressing.
Best Practices
Nevertheless, you probably still wonder how this all comes together. Exceptions may seem like a useful tool, but how do you really use them in your code?
Use Exceptions For Error Handling
Write exceptions to handle errors and unexpected conditions that occur during the execution of your code. This makes it easier to identify and fix problems and makes the code more readable and maintainable.
Raise Exceptions When Appropriate
When you encounter an error or unexpected condition, raise an exception to indicate something has gone wrong. This allows the calling code to catch the exception and handle it appropriately.
Catch Exceptions Where You Can Handle Them
When you catch an exception, you should handle it in a way that makes sense for your code. For example, you might log the error, show an error message to the user, or simply continue processing.
Use Specific Exceptions
Whenever possible, use specific exceptions instead of generic exceptions like Exception. This makes it easier to catch and handle specific types of errors and makes the code more readable and maintainable.
Remember that you can quickly create custom exceptions that allow you to be even more specific with catching them.
Define Custom Exceptions Early
If you're planning to use custom exceptions in your code, define them at the top of your script. This helps in two ways:
- Reusability: You can use the custom exception throughout your script.
- Readability: It'll be less complicated to understand what the custom exception object is if you can quickly find it at the top of your script.
You don't need to know beforehand whether or not you'll need a custom exception. But once you decide that you want to use one, write it at the top of your script and give it a descriptive docstring.
Avoid Catching Too Broad Exceptions
You may feel tempted to catch broad exceptions or even the base Exception object to catch all possible errors. However, this can make it difficult to identify the cause of the error and can hide bugs in your code. It's better to catch only the exceptions that you can actually handle and let the others propagate up the call stack.
Summary: How to Use Python Exceptions
- Use exceptions for error handling
- Raise exceptions when appropriate
- Catch exceptions where you can handle them
- Use specific exceptions
- Define custom exceptions early
- Avoid catching too broad exceptions