[Python-Dev] Re: PEP-317

[Guido van Rossum]

> Quoth Guido van Rossum:
>   [...]
> > Python usually doesn't care about isinstance relationships but cares
> > about whether the needed protocol is implemented, and this suggests
> > that requiring exceptions to subclass Exception is unPythonic.

[Steven T]
> This came up in python-list not long ago [1], and I raised (heh)
> exactly that argument.  Alex Martelli counterargued that
> exceptions are one area in which we *do* usually care about
> isinstance relationships, since that's how we specify which
> exceptions to catch.
> 
> [1] http://mail.python.org/pipermail/python-list/2003-May/160965.html

Excellent argument.  Thanks, Steve and Alex.

--Guido van Rossum (home page: http://www.python.org/~guido/)