Nested function scope problem

[Terry Reedy]

"Dennis Lee Bieber" <wlfraed at ix.netcom.com> wrote in message 
news:7fnbc21742p5kcfis5b9sobtsvvqmmm98v at 4ax.com...
> The names in the parameter list of the "def" statement are bound to
> the objects associated with the actual call. After that, they behave
> very much as locals... Now -- with defaults it gets a touch trickier...

A function's parameters are not just 'very much as locals', they *are* 
locals.
>>> def f(x): print locals()

>>> f(3)
{'x': 3}

In particular, parameters are just those locals that are initialized in the 
call process; it is an error for a parameter name to not become bound to 
some object.  The default objects fill in the slack when there are not 
enough argument objects.

>From the calling side, the arguments are objects to be used in that initial 
binding process, either directly or as part of a new collective object.  It 
is an error for an argument to not be used.  The calling code does not care 
about the parameter names, but just their number and nature.

So one can think of calling as cross-namespace name binding followed by 
control transfer.  Returning is similar except that return objects may 
ignored or bound to slots rather than names.

Terry Jan Reedy