On 22Apr2019 1921, Steve Dower wrote:
On 22Apr2019 1822, Glenn Linderman wrote:
Inada is now proposing a way to allow the coder to suggest a group of
dictionaries that might benefit from the same gains, by preclassifying
non-__dict__ slot dictionaries to do similar sharing.
CSV reader is an exemplary candidate, because it creates groups of
dicts that use the same keys. (column names). I have other code that
does similar things, that would get similar benefits.
Seems like since it is just an interface to existing builtin code,
that the one interface function (or dictionary factory class) could
just as well be a builtin function, instead of requiring an import.
Sounds like a similar optimisation to sys.intern() is for strings.
I see no reason to try and avoid an import here - it's definitely a
special-case situation - but otherwise having a function to say "clone
and update this dict" that starts by sharing the keys in the same way
that __dict__ does (including the transformation when necessary) seems
like an okay addition. Maybe copy() could just be enabled for this?
Or possibly just "dict(existing_dict).update(new_items)".
My primary concern is still to avoid making CPython performance
characteristics part of the Python language definition. That only makes
it harder for alternate implementations. (Even though I was out-voted
last time on this issue since all the publicly-known alternate
implementations said it would be okay... I'm still going to put in a
vote for avoiding new language semantics for the sake of a single
runtime's performance characteristics.)
Cheers,
Steve
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