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

[Daniel Urban]

> BoundArguments Object
> =====================
>
> Result of a ``Signature.bind`` call.  Holds the mapping of arguments
> to the function's parameters.

The Signature.bind function has changed since the previous version of
the PEP. If I understand correctly, the 'arguments' attribute is the
same as the return value of bind in the previous version (more or less
the same as the return value of inspect.getcallargs). My question is:
why we need the other 2 attributes ('args' and 'kwargs')? The
"Annotation Checker" example uses it to call the function. But if we
are able to call bind, we already have the arguments, so we can simply
call the function with them, we don't really need these attributes. I
think it would be better (easier to use and understand), if bind would
simply return the mapping, as in the previous version of the PEP.

> Has the following public attributes:
>
> * arguments : OrderedDict
>     An ordered mutable mapping of parameters' names to arguments' values.
>     Does not contain arguments' default values.

Does this mean, that if the arguments passed to bind doesn't contain a
value for an argument that has a default value, then the returned
mapping won't contain that argument? If so, why not?
inspect.getcallargs works fine with default values.


Daniel