[Python-Dev] Proposal: dict.with_values(iterable)

[Steve Dower]

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?

Cheers,
Steve