There are a number of built-in exceptions that represent warning categories. This categorization is useful to be able to filter out groups of warnings. The following warnings category classes are currently defined:
|Warning||This is the base class of all warning category classes. It is a subclass of Exception.|
|UserWarning||The default category for warn().|
|DeprecationWarning||Base category for warnings about deprecated features.|
|SyntaxWarning||Base category for warnings about dubious syntactic features.|
|RuntimeWarning||Base category for warnings about dubious runtime features.|
|FutureWarning||Base category for warnings about constructs that will change semantically in the future.|
|PendingDeprecationWarning||Base category for warnings about features that will be deprecated in the future (ignored by default).|
|ImportWarning||Base category for warnings triggered during the process of importing a module (ignored by default).|
|UnicodeWarning||Base category for warnings related to Unicode.|
While these are technically built-in exceptions, they are documented here, because conceptually they belong to the warnings mechanism.
User code can define additional warning categories by subclassing one of the standard warning categories. A warning category must always be a subclass of the Warning class.
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