The next release of kwkey will provide a class A with the following
property.
It is that
>>> A(1, 2, a=3, b=4)[d] = 'val'
will result in
>>> d.__setitem__((1, 2), 'val', a=3, b=4)
This is precisely the same call that would result from
>>> d[1, 2, a=3, b=4] = 'val'
using the semantics that Guido currently favours.
Further, to better support exploration, the call instead will be
>>> d._A_setitem__((1, 2), 'val', a=3, b=4)
when d._A_setitem__ exists. (And of course similar behaviour for getitem
and delitem.)
This will allow experiments via subclassing an existing class, for example
from xarray. Using _A_setitem__ etc means that the new
>>> A(1, 2, a=3, b=4)[d] = 'val'
semantics can be implemented via the already existing
>>> d[SOMETHING] = 'val'
implementation.
Both the commands
>>> d[SOMETHING] = 'val'
>>> A(1, 2, a=3, b=4)[d] = 'val'
can thus work on the same mapping / sequence instance d. The two
implementations can peacefully co-exist.
For clarity, when available
>>> d[1, 2, a=3, b=4] = 'val'
is most likely to be better than
>>> A(1, 2, a=3, b=4)[d] = 'val'
and I introduce the A second form as a useful stopgap, until the first form
is available.
A reminder. The purpose of kwkey is to provide a convenient way for people
to experiment with different approaches to implementing the semantics of
>>> d[1, 2, a=3, b=4] = 'val'
and, perhaps, to provide a compatible implementation in present day Python.
For fairness, I hope also to provide a class B that supports the __keyfn__
semantics.
I hope to make this release next week. Comments are welcome.
https://pypi.org/project/kwkey/
https://github.com/jfine2358/python-kwkey/issues/3
--
Jonathan
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