raise Statements
Introduction to raise Statements
In Python programming, errors and exceptions are part of the routine process and act as debug-friendly alerts. To invoke exceptions manually or highlight exigent conditions, Python allows the usage of raise
statements.
The raise
statement, in Python, allows the programmer to force a specified exception to occur. It gives the ability to stop program execution when an external condition is triggered or when a bug is introduced.
Building of raise Statements
Here’s how a raise
statement is typically built:
In the example above, ‘Exception’ is a built-in, base class for all exceptions and “Description of the error/ exception” is an informative message that explains the cause of the error.
Implementing raise Statements in Python
Let’s look at a simple implementation of the raise
statement in Python:
In this code, we’re raising an exception when the variable x
is less than 0. Hence, running this code would throw an error, Exception: Sorry, no numbers below zero
.
Custom Exceptions
Generally, Python’s built-in exceptions are used to raise exceptions. Nevertheless, users can also define their own exceptions by creating a new exception class which inherits from the base Exception
class.
Here is an example demonstrating how this can be done:
In the example above, CustomError
is our own exception class which is derived from Python’s exception base class, Exception
.
Note
The pass
in Python means “do nothing”. It is used when a statement is required syntactically but the program requires no action.
Remember, the choices of handling exceptions entirely depend on the needs of your specific program. Being proficient with Python’s error and exception handling can greatly improve the robustness of your code. Keep experimenting!