[Python-Dev] Updated PEP 362 (Function Signature Object)

[Nick Coghlan]

On Thu, Jun 7, 2012 at 11:28 PM, Michael Foord
<fuzzyman at voidspace.org.uk> wrote:
>> We'll probably extend it to copy __signature__ too; then 'signature(decor(f))'
>> will be the same as 'signature(f)'.
>
> I don't think functools.wraps can copy the signature by default - it's not uncommon to have decorators that modify signatures. A new parameter to functools.wraps defaulting to False?

Most wrapped functions already report the wrong signature under
introspection anyway (typically (*args, **kwds)). Following the
__wrapped__ chains by default will produce an answer that is more
likely to be correct in such cases.

The big win from my point of view is that thanks to __signature__,
decorators that modify the signature will now have the opportunity to
retrieve the signature from the underlying function and accurately
report a *different* signature.

Cheers,
Nick.

-- 
Nick Coghlan   |   ncoghlan at gmail.com   |   Brisbane, Australia