On 3/22/2019 12:53 AM, Steven D'Aprano wrote:
On Thu, Mar 21, 2019 at 09:36:20PM -0400, Terry Reedy wrote:
I counted what I believe to be 10 instances of copy-update in the top
level of /lib. Do either of you consider this to be enough that any
addition would be worthwhile.
I think you're referring to Guido and Antoine?
Yes, those were the two (core-devs) I quoted, and perhaps had missed my
post, while you already thanked me for collecting some date.
But for what it's worth,
I think that's a good indication that there are uses for a merge
operator.
Some, yes. Enough for new syntax? What is a reasonable standard? Are
there existing syntax features so sparsely used? What is the bar for
something that adds no new function, but saves 6 chars and is easier to
understand for at least some?
In the past, 'Would this be used in the stdlib?' has been asked of
feature proposals. But I never paid attention past == 0 or > 0. When
Guido approved ':=', what threashhold of usefulness did he use? How
many uses of ':=' does he anticipate, or consider enough to justify the
addition?
There are 3 in idlelib that I plan to replace with {**a, **b} and be
done with the issue. I did not check any other packages.
If a+b already worked for dicts, would you still prefer {**a, **b}?
Example: {**sys.modules, **globals()}
Aside from the fact that I can patch *and* backport to 3.7 *now*, I
think so. The latter clearly (to me) maps mappings to a dict.
How about if it were spelled a|b?
As in sys.modules | globals() or (sys.modules | globals())? Closer.
--
Terry Jan Reedy
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