[Python-3000] pep 3124 plans

[Jim Jewett]

On 7/21/07, Phillip J. Eby <pje at telecommunity.com> wrote:

>... If you have to use @somegeneric.before and
> @somegeneric.after, you can't decide on your own to add
> @somegeneric.debug.

> However, if it's @before(somegeneric...), then you can add
> @debug and @authorize and @discount and whatever else
> you need for your
> application, without needing to monkeypatch them in.

I honestly don't see any difference here.  @somegeneric.method implies
that somegeneric is an existing object, and even that it already has
rules for combining .before and .after; it can just as easily have a
rule for combining arbitrary methods.

If you're saying that @discount could include its own combination
rules, then each method needs to repeat the boilerplate to pick apart
the current decision tree.  The only compensating "advantage" I see is
that the decision tree could be changed arbitrarily from anywhere,
even as "good practice."  (Since my new @thumpit decorator would takes
the generic as an argument, you won't see the name of the generic in
my file; you might never see it there was iteration involved.)

> Our brains run by pattern recognition, with more-specific
> patterns taking precedence, so this is an easier model for your
> brain to follow than step-by-step computation anyway.

Only if you are confident that you have all the patterns enumerated.

I realize that subclasses are theoretically just as arbitrary, but
they aren't in practice.  Base classes are almost always named
directly, rather than indirectly through a variable.  Subclassing
(normally) affects only the first dimension, so you don't have a
cartesian product to mentally resolve.

You can certainly say now that configuration specialization should be
in one place, and that dispatching on parameter patterns like

(*            # ignored
, :int        # actual int subclass
, :Container  # meets the Container ABC
, 4<val<17.3  # value-specific rule
)

is a bad idea -- but whenever I look at an application from the
outside, well-organized configuration data is a rare exception.

> At 10:55 PM 7/20/2007 -0700, Talin wrote:
> >If it turns out that there's no way to get a callback when the
> >class has finished being built,

Could you clarify why the __class__ attribute being used by super is
not sufficient?

-jJ