[Python-Dev] Adding functools.decorator

Guido van Rossum guido at python.org
Sun Apr 30 18:36:54 CEST 2006


On 4/30/06, Georg Brandl <g.brandl at gmx.net> wrote:
> Nick Coghlan wrote:
> > Collin Winters has done the work necessary to rename PEP 309's functional
> > module to functools and posted the details to SF [1].
> >
> > I'd like to take that patch, tweak it so the C module is built as _functools
> > rather than functools, and then add a functools.py consisting of:
>
> I'm all for it. (You could integrate the C version of "decorator" from my SF
> patch, but I think Python-only is enough).

Stronger -- this should *not* be implemented in C. There's no
performance need, and the C code is much harder to understand, check,
and modify.

I expect that at some point people will want to tweak what gets copied
by _update_wrapper() -- e.g. some attributes may need to be
deep-copied, or personalized, or skipped, etc. (Doesn't this already
apply to __decorator__ and __decorates__? I can't prove to myself that
these get set to the right things when several decorators are stacked
on top of each other.)

I'm curious if @decorator is the right name and the right API for this
though? The name is overly wide (many things are decorators but should
not be decorated with @decorator) and I wonder of a manual call to
_update_wrapper() wouldn't be just as useful. (Perhaps with a simpler
API -- I'm tempted to call YAGNI on the __decorator__ and
__decorates__ attributes.)

I think there are too many design options here to check this in
without more discussion.

--
--Guido van Rossum (home page: http://www.python.org/~guido/)


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