How to throw custom exception?

By creating a custom exception class, inheriting from Exception or its subclass, and defining a constructor in it that passes in error information, you can instantiate the class using the throw keyword when an exception is thrown. In a practical use case, this method can be used to throw a custom exception to provide a clear error message to the user when non-compliant input is detected.

How to throw a custom exception?

Throwing custom exceptions allows you to create custom error messages to aid development and debugging.

Steps:

1. Create a custom exception class that inherits from Exception or its subclasses.
2. In the exception class, define a constructor and initialize it by passing in error information.
3. When throwing an exception, use the throw keyword and instantiate the custom exception class.

Code example:

class CustomException(Exception):
    def __init__(self, message):
        super().__init__(message)


# 抛出自定义异常
try:
    raise CustomException("发生了错误！")
except CustomException as e:
    print(e)  # 输出 "发生了错误！"

Practical case:

Suppose you have a function to verify the user enter. If the input does not meet the requirements, you want to throw a custom exception.

def validate_input(input):
    if not input:
        raise CustomException("输入不能为空！")

When a function detects a null input, it throws a CustomException with the error message "The input cannot be null!".

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