On Sun, Apr 08, 2018 at 09:25:33PM +1000, Nick Coghlan wrote:
> I was writing a new stdlib test case today, and thinking about how I
> might structure it differently in a PEP 572 world, and realised that a
> situation the next version of the PEP should discuss is this one:
>
> # Dict display
> data = {
> key_a: 1,
> key_b: 2,
> key_c: 3,
> }
>
> # Set display with local name bindings
> data = {
> local_a := 1,
> local_b := 2,
> local_c := 3,
> }
I don't understand the point of these examples. Sure, I guess they would
be legal, but unless you're actually going to use the name bindings,
what's the point in defining them?
data = {
1,
(spam := complex_expression),
spam+1,
spam*2,
}
which I think is cleaner than the existing alternative of defining spam
outside of the set.
And for dicts:
d = {
'key': 'value',
(spam := calculated_key): (eggs := calculated_value),
spam.lower(): eggs.upper(),
}
> I don't think this is bad (although the interaction with dicts is a
> bit odd), and I don't think it counts as a rationale either, but I do
> think the fact that it becomes possible should be noted as an outcome
> arising from the "No sublocal scoping" semantics.
If we really wanted to keep the sublocal scoping, we could make
list/set/dict displays their own scope too.
Personally, that's the only argument for sublocal scoping that I like
yet: what happens inside a display should remain inside the display, and
not leak out into the function.
So that has taken me from -1 on sublocal scoping to -0.5 if it applies
to displays.
--
Steve
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