[Zope3-dev] interface conventions: default=_RAISE_ERROR

[Barry A. Warsaw]

>>>>> "GvR" == Guido van Rossum <guido@python.org> writes:

    >> So if you had to do it over again, what would the
    >> signature/semantics of getattr() be?

    GvR> Not sure, but perhaps getattrdefault(obj, name, default) for
    GvR> the 3-arg version and getattr(obj, name) for the 2-arg
    GvR> version that raises an exception when obj.<name> doesn't
    GvR> exist.

    GvR> BTW, I take it back that 50% of the getattr() calls in the
    GvR> stdlib don't catch the exception.  It's probably closer to
    GvR> 90% -- the 3-arg variant is truly rare, and the 2-arg variant
    GvR> inside try/except is pretty rare.

I think that matches my own experiences.  I tend to use getattr()
itself in introspective situations, where I'm trying to sniff at an
object to see if it supports a particular interface (method) or not.
In the face of formal Interfaces, its use altogether may diminish (in
library code, if not in the Python core).

-Barry