[Python-ideas] Re: PEP 671 (late-bound arg defaults), next round of discussion!

On Thu, Dec 02, 2021 at 08:29:58AM +0000, Paul Moore wrote:

1. It's hard (if not impossible) to wrap functions that use late-bound

defaults.

I don't understand that argument.

We can implement late-bound defaults right now, using the usual sentinel jiggery-pokery.

def func(spam, eggs, cheese=None, aardvark=42): if cheese is None: ... # You know the drill.

We can wrap functions like this. You don't generally even care what the sentinel is. A typical wrapper function looks something like this:

@functools.wraps(func) def inner(*args, **kwargs): # wrapper implementation func(*args, **kwargs)

with appropriate pre-processing or post-processing as needed.

Why would argument unpacking to call the wrapped function stop working?