[Python-3000] Traits/roles instead of ABCs (original) (raw)

Steven Bethard steven.bethard at gmail.com
Mon Apr 30 20:21:24 CEST 2007

On 4/30/07, Collin Winter <collinw at gmail.com> wrote:

On 4/30/07, Steven Bethard <steven.bethard at gmail.com> wrote: > On 4/30/07, Collin Winter <collinw at gmail.com> wrote: > > No existing mechanism would allow PEP 3141 to be distributed as a > > third-party module and still impact the built-in types; that's what > > this whole business of isinstance and issubclass is about. In > > order to achieve dynamic composition, we're having to monkey with > > fundamental, bedrock properties of inheritance-based object > > orientation. The definition of "subclass" and "instance" is no longer > > objective; the answer to "is X an instance of Y?" becomes, "I dunno, > > ask Y". > > I guess I don't understand why this bothers you more than how you can > currently mess with class:: [snip] > Maybe you could give a couple realistic examples of where you think > people using isinstance and issubclass are going to break > things unintentionally?

You assume that being able to change class doesn't bother me: it does. The thing that mitigates my unease is that it comes with a gigantic red flag that boils down to, "Don't even think about this unless you're implementing proxy objects".

Ahh. I guess I see isinstance and issubclass as having gigantic red flags saying "Don't even think about these unless you're implementing ABCs". ;-)

STeVe

I'm not in-sane. Indeed, I am so far out of sane that you appear a tiny blip on the distant coast of sanity. --- Bucky Katt, Get Fuzzy

More information about the Python-3000 mailing list