Understanding Exception Handling in C#: Can We Only Throw Exceptions in Functions?

Explore the mechanics of exception handling in C-, focusing on whether exceptions can only be thrown in function definitions and how to properly implement them.
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Understanding Exception Handling in C-: Can We Only Throw Exceptions in Functions?

When developing applications in C-, developers often face scenarios where they need to manage exceptional cases—events that are not part of the normal flow of execution. A common question arises: can exceptions only be thrown in function definitions? This question stems from a developer's experience trying to throw a custom exception when certain conditions are met but encountering unexpected behavior.

The Scenario: Custom Exception for Parking Duration

In this example, we have a custom exception ParkingException, which is meant to indicate that a car has been towed if it is parked for more than 24 hours. The developer initially attempted to throw this exception in a property setter called HoursParked, but it did not behave as expected. However, when the check was moved to a separate function, it worked flawlessly.

Example Code Snippet

Here is the relevant portion of the code:

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Solution: Proper Implementation of Exception Handling

Exceptions Are for Exceptional Situations

Understanding Context: Exceptions should only be thrown when the code encounters an unexpected or erroneous situation. If a value is outside the defined acceptable range, that's a valid scenario to throw an exception.

Properties and Functions:

While you can throw exceptions in both properties and functions, the context matters. Properties are generally used to get or set values without side effects.

When conditions are violated (like the parking hours exceeding 24), using property setters can lead to unexpected behavior if not properly handled. It often leads to looking at the return value rather than throwing its own exceptions.

Better Practice in Exception Handling

Below is the refined implementation:

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Key Takeaways

Use Functions for Critical Operations: Consider throwing exceptions in functions that are intended to perform critical calculations or checks, as they are typically better suited for handling operational logic.

Properties for Basic Getter/Setter: Keep properties lean. They should ideally just store or return values without throwing exceptions unless crucial validations are necessary.

Customize Exception Messages: Always provide clear and informative messages with your exceptions to make debugging easier.

Conclusion

So, to answer the question: can we only throw exceptions in function definitions? Not exclusively, but it is highly recommended to manage exceptions in a disciplined manner by using functions for validation and processing. This promotes cleaner, more maintainable code and enhances the overall user experience by providing clear error handling paths.

By understanding and applying proper exception handling rules, developers can create robust applications that handle errors gracefully while providing clear feedback to users.