The Perplexity of Custom Exception Declarations in Python
In the realm of Python exception handling, the declaration of custom exception classes has undergone significant revisions. To align with contemporary best practices, it is crucial to comprehend the current conventions.
Custom Exception Classes with Extra Data
To incorporate additional data into custom exceptions, it is now recommended to override the init method, passing any desired information as arguments. For example:
class ValidationError(Exception): def __init__(self, message, errors): # Call the base class constructor with required parameters super().__init__(message) # Include custom data self.errors = errors
This approach allows the retrieval of extra data later using e.errors.
Avoiding the Deprecation Warning
The deprecation of BaseException.message has introduced a potential pitfall. To avoid this warning, it is imperative to refrain from using the message attribute directly. Instead, override the str__, __unicode__, and __repr methods to control the representation of the exception message.
Utilizing args vs. Positional Arguments
In previous versions of Python, the use of *args was recommended for passing additional arguments to exception constructors. However, in Python 3, positional arguments should be used instead. This allows for more explicit and robust code.
class ValidationError(Exception): def __init__(self, message, errors): super().__init__(message) self.errors = errors
By adhering to these principles, developers can craft custom exception classes that fully comply with modern Python standards and maintain compatibility with existing exception handling tools.
The above is the detailed content of How Should I Design Custom Exceptions in Modern Python?. For more information, please follow other related articles on the PHP Chinese website!

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