function attributes are like function objects

[Fredrik Lundh]

Tim Peters wrote:
> Yes, and if you *showed* that one-liner, the "easier" would be shot all to
> pieces.  These aren't meant to be write-only attributes <wink>.

here's how I would solve your publishing example:

ALWAYS = "ALWAYS"
SOMETIMES = "SOMETIMES"

#
# user code

class ClassicSpam:

    publish = {}

    def egg(self, x):
        pass
    publish[egg] = ALWAYS
    # 2.1: egg.publish = ALWAYS

class NewSpam(ClassicSpam):

    publish = {}

    def bacon(self, x):
        pass
    publish[bacon] = SOMETIMES
    # 2.1: bacon.publish = SOMETIMES

#
# code for the publisher framework

def getpublish(klass, name):
    # figure out if/when we can publish this method
    try:
        method = getattr(klass, name)
        return method.im_class.publish[method.im_func]
        # 2.1: return method.publish
    except (AttributeError, KeyError):
        return None # nope

#
# try it out

for function in ["bacon", "egg", "spam"]:
    print function, getpublish(NewSpam, function)

advantages:
+ works with pre-2.1 python
+ requires one dictionary per class instead of one
  per method
+ no memory penalty for classes that doesn't belong
  to the publishing framework

disadvantages:
+ the 1-3 lines you need to dig out the attribute
  varies slightly, depending on the application

> > On the other hand, this isn't such a big deal, especially not com-
> > pared to some of the stuff I've seen on python-dev lately.  I'm
> > pretty sure a third-party python implementer can ignore function
> > attributes, and nobody will ever notice...
>
> We would certainly notice the absence of function.__doc__,
> and any 3rd-party implementer realizing that first would likely
> take a much more uniform approach to implementing object
>> attributes than did Guido at the start.

not so sure about that -- __doc__ strings are very common,
and are better stored in a separate slot to save memory (just
like CPython does, of course).

and I doubt many people would notice if __doc__ were made
readonly...

Cheers /F