[docs] [issue23764] Reference inspect.Signature.bind from functools.wraps documentation

Nick Coghlan report at bugs.python.org
Thu Mar 26 02:05:34 CET 2015

Nick Coghlan added the comment:

Ah, unfortunately, on closer inspection, even partial itself ends up suffering from the same problem as the current inspect.wraps - validation ultimately happens at the point of calling the original wrapper function, so if you don't actually call it, you won't get any argument validation.

You can use https://docs.python.org/3/library/inspect.html#inspect.Signature.bind to force early validation without actually calling the underlying callable, but that's always going to be substantially slower than "just try it and see if it works". functools is also further down in the stdlib dependency hierarchy than the inspect module so it isn't possible to offer that behaviour without creating a circular dependency.

What would be possible is to point out explicitly that "wraps" only updates introspection metadata, and if you're after eager argument validation (e.g. before queuing a command for delayed execution), then you likely want inspect.Signature.bind.

assignee:  -> docs at python
components: +Documentation -Library (Lib)
nosy: +docs at python
title: Accept a separate "call_target" parameter to functools.partial -> Reference inspect.Signature.bind from functools.wraps documentation
versions: +Python 3.4

Python tracker <report at bugs.python.org>

More information about the docs mailing list