[Python-Dev] PEP 348 and ControlFlow
eric.nieuwland at xs4all.nl
Tue Aug 9 22:32:50 CEST 2005
Sorry to bring this up again, but I think there is an inconsistency in
PEP 348 in its current formulation.
From PEP: "In Python 2.4, a bare except clause will catch any and all
exceptions. Typically, though, this is not what is truly desired. More
often than not one wants to catch all error exceptions that do not
signify a "bad" interpreter state. In the new exception hierarchy this
is condition is embodied by Exception. Thus bare except clauses will
catch only exceptions inheriting from Exception."
So, bare except will catch anything that is an Exception. This
includes GeneratorExit and StopIteration, which contradicts: "It has
been suggested that ControlFlowException should inherit from Exception.
This idea has been rejected based on the thinking that control flow
exceptions typically should not be caught by bare except clauses,
whereas Exception subclasses should be."
To me this means GeneratorExit and StopIteration are to be taken out of
the Exception subtree. It seems to me rather awkward to put them at the
same level as Exception and TerminatingException. So there comes the
old (yeah, I know REJECTED) idea of a ControlFlowException class, right
next to Exception and TerminatingException:
Is my logic flawed (again ;-)?
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