* In https://www.python.org/dev/peps/pep-0654/#programming-without-except, the
natural way isn't shown:
try:
<smth>
except (MultiError, ValueError) as e:
def _handle(e):
if isinstance(e, ValueError):
return None
else:
return exc
MultiError.filter(_handle,e)
So a statement that the current handling is "cumbersome" and "unintuitive" is
unconvincing.
If this results in lots of boilerplate code with isinstance(), filter() can be changed to e.g. accept a dict of exception types and
handlers. Actually, I wonder why you didn't do that already if handling specific exception types and reraising the rest is the standard
procedure!
Then the code would be reduced to:
try:
<smth>
except (MultiError, ValueError) as e:
MultiError.filter({ValueError: lambda _: None},
e)
* https://github.com/python-trio/trio/issues/611 says that it somehow causes
problems with 3rd-party libraries -- but there's no
explanation how -- either there or in the PEP.
If some code doesn't know about MultiError's, it should handle one like any other unknown exception that it cannot do anything intelligent
about.
If it wishes to handle them, you need to split MultiError into a separate library that anyone could use without having to pull the entire
`trio`.
On 23.02.2021 3:24, Irit Katriel via Python-Dev wrote:
Hi all,
We would like to request feedback on PEP 654 -- Exception Groups and except*.
https://www.python.org/dev/peps/pep-0654/
<https://www.python.org/dev/peps/pep-0654/>
It proposes language extensions that allow programs to raise and handle
multiple unrelated
exceptions simultaneously, motivated by the needs of asyncio and other
concurrency libraries,
but with other use cases as well.
* A new standard exception type, ExceptionGroup, to represent multiple
exceptions with
shared traceback.
* Updates to the traceback printing code to display (possibly nested)
ExceptionGroups.
* A new syntax except* for handling ExceptionGroups.
A reference implementation (unreviewed) can be found at:
https://github.com/iritkatriel/cpython/pull/10
<https://github.com/iritkatriel/cpython/pull/10>
Thank you for your help
Kind regards
Irit, Yury & Guido
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--
Regards,
Ivan
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