[Python-Dev] exception chaining (original) (raw)

Ethan Furman ethan at stoneleaf.us
Fri Jan 20 18:09:57 CET 2012

Summary:

Exception Chaining is cool, unless you are writing libraries that want to transform from Exception X to Exception Y as the the previous exception context is unnecessary, potentially confusing, and cluttery (yup, just made that word up!).

For all the gory details, see http://bugs.python.org/issue6210.

I'm going to attempt a patch implementing MRAB's suggestion:

try: some_op except ValueError: raise as OtherError() # raise keeps context, raise as does not

The question I have at the moment is: should raise as be an error if no exception is currently being handled?

Example:

def smurfy(x): if x != 'magic flute': raise as WrongInstrument do_something_with_x

If this is allowed then smurfy could be called from inside an except clause or outside it.

I don't care for it for two reasons:

Other thoughts?

Ethan

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