On Thu, Nov 7, 2013 at 2:20 PM, Eric Snow <ericsnowcurren...@gmail.com>wrote:
> On Thu, Nov 7, 2013 at 11:44 AM, Brett Cannon <br...@python.org> wrote: > > Lazy message creation through > > __str__ does leave the message out of `args`, though. > > If that's an issue you could make args a (settable) property that > dynmically returns str(self) if appropriate: > > @property > def args(self): > actual = super().args > if actual or self.name is None: > return actual > return (str(self),) > Good point. That would solve that backwards-compatibility issue and allow the raising of DeprecationWarning. > > > > > In a perfect world (Python 4 maybe?) BaseException would take a single > > argument which would be an optional message, `args` wouldn't exist, and > > people called `str(exc)` to get the message for the exception. That would > > allow subclasses to expand the API with keyword-only arguments to carry > > extra info and have reasonable default messages that were built on-demand > > when __str__ was called. It would also keep `args` from just being a > dumping > > ground of stuff that has no structure except by calling convention > (which is > > not how to do an API; explicit > implicit and all). IOW the original > dream > > of PEP 352 (http://python.org/dev/peps/pep-0352/#retracted-ideas). > > This reminds me that I need to revisit that idea of reimplementing all > the builtin exceptions in pure Python. :) > Ah, that idea. =) Definitely a question of performance.
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