[Python-ideas] Namespace creation with syntax short form

[Peter Otten]

Steven D'Aprano wrote:

> On Fri, Feb 13, 2015 at 11:19:58AM +0100, Morten Z wrote:
>> Namespaces are widely used in Python, but it appear that creating a
>> namespace
>> has no short form, like [] for list or {} for dict, but requires the
>> lengthy types.SimpleNamespace, with prior import of types.
> 
> from types import SimpleNamespace as NS
> ns = NS(answer=42)
> 
> Python did without a SimpleNamespace type for 20+ years. I don't think
> it is important enough to deserve dedicated syntax, especially yet
> another overloading of parentheses. Not everything needs to be syntax.

If there were syntactic support for on-the-fly namespace "packing" and 
"unpacking" that could have a significant impact on coding style, similar to 
that of named arguments.

Functions often start out returning a tuple and are later modified to return 
a NamedTuple. For backward compatibility reasons you are either stuck with 
the original data or you need a workaround like os.stat_result which has 
more attributes than items. "Named (un)packing" could avoid that.

>>> def f():
...    return a:1, b:2, c:3
>>> f()
(a:1, b:2, c:3)
>>> :c, :b, :a = f() # order doesn't matter
>>> :a, :c = f()     # we don't care about b
>>> a                # by default bound name matches attribute name
1
>>> x:a, y:c = f()   # we want a different name
>>> x, y
(1, 3)