== Why is this an issue?

In Python 3, attempting to raise an object which does not derive from BaseException will raise a ``++TypeError++``. In Python 2 it is possible to raise old-style classes but this shouldn't be done anymore in order to be compatible with Python 3.


If you are about to create a custom Exception class, note that custom exceptions should inherit from ``++Exception++``, not ``++BaseException++``. ``++Exception++`` allows people to catch all exceptions except the ones explicitly asking the interpreter to stop, such as ``++KeyboardInterrupt++`` and https://docs.python.org/3/library/exceptions.html#GeneratorExit[``++GeneratorExit++``] which is not an error. See https://www.python.org/dev/peps/pep-0352/#exception-hierarchy-changes[PEP 352] for more information.


This rule raises an issue when an object which doesn't derive from BaseException is raised.


=== Noncompliant code example

[source,python]
----
raise "Something went wrong"  # Noncompliant

class A:
    pass

raise A  # Noncompliant
----


=== Compliant solution

[source,python]
----
class MyError(Exception):
    pass

raise MyError("Something went wrong")
raise MyError
----


== Resources

* https://docs.python.org/3/tutorial/errors.html[Python documentation - Errors and Exceptions]
* https://www.python.org/dev/peps/pep-0352/#exception-hierarchy-changes[PEP 352 - Required Superclass for Exceptions]

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'''
== Implementation Specification
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=== Message

Change this code so that it raises an object deriving from BaseException.


'''
== Comments And Links
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include::../comments-and-links.adoc[]
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