[Python-ideas] PEP-3151 pattern-matching

[dag.odenhall at gmail.com]

On 19 May 2011 00:13, Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> Devin Jeanpierre wrote:
>>
>> On Wed, May 18, 2011 at 6:07 AM, dag.odenhall at gmail.com
>> <dag.odenhall at gmail.com> wrote:
>>
>>> except IOError(32):  # isinstance IOError and .args == (32,)
>>>  ...
>>
>> Unfortunately, as described it wouldn't match IOError(32, 'Blah blah
>> blah').
>
> Also it's a bit magical -- normally one doesn't expect
> Haskell-like pattern matching in Python.
>
> Maybe something more explicit would be better:
>
>  try:
>    ...
>  except IOError as e with e.errno == 32:
>    ...

Then we're back where we started in which case I prefer 'if' as the keyword.