[Python-Dev] Adding functools.decorator (original) (raw)

Georg Brandl g.brandl at gmx.net
Sun Apr 30 19:09:29 CEST 2006

Guido van Rossum wrote:

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.

+1.

I expect that at some point people will want to tweak what gets copied by updatewrapper() -- e.g. some attributes may need to be deep-copied, or personalized, or skipped, etc.

What exactly do you have in mind there? If someone wants to achieve this, she can write his own version of @decorator.

One thing that would be nice to copy is the signature, but for that, like demonstrated by Simon Belak, exec trickery is necessary, and I think that's one step too far.

The basic wish is just to let introspective tools, and perhaps APIs that rely on function's name and doc work flawlessly with decorators applied, nothing more.

(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 don't think they're necessary.

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 updatewrapper() wouldn't be just as useful.

Still, _update_wrapper would need to be defined somewhere, and it would have to be called in the body of the decorator.

(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.

So let the discussion begin!

Georg

More information about the Python-Dev mailing list