On Sat, Jul 11, 2020 at 3:45 PM Christopher Barker <python...@gmail.com>
wrote:
> On Fri, Jul 10, 2020 at 12:45 PM David Mertz <me...@gnosis.cx> wrote:
> > The strongest argument I've seen is: `list(d.items())` adds six
> characters.
>
> 1) Matching our mental model / usability: if I want the nth item (or a
> random item) from a dict, I want to ask for that -- I don't want to make a
> list, just to index it and throw it away. the list(d.items()) idiom is the
> right one if I actually need a list -- it's a bit awkward to have to make a
> list, just to throw it away. 2) Performance: making an entire list just to
> get one item out is a potentially expensive operation. Again, for the
> limited use cases, probably not a big deal, I'm having a really hard time
> imagining a application where that would be a bottleneck, but it is *a*
> reason, if not a compelling one.
>
For the single case of wanting JUST ONE random key/val pair from a
dictionary EVER, I agree random.choice(d.items()) looks a little better. I
even agree that it's something that probably seems obvious to try the first
time.
However, once you want to get multiple items, the amortized costs starts to
matter. I think that latter situation is likely to be VASTLY more common
in real code... but I'm just saying that without evidence. Still, this is
such a narrow situation, I just don't see it as justifying a language
change (the "get an item, only once" case).
Code that I can easily imagine writing (although I'm not sure I actually
have):
items = dict.items()
while True:
k, v = random.choice(items)
if satisfies_need(k, v):
do_stuff(k, v)
break
The hypothetical view-sequence would be an attractive nuisance that would
hurt performance in all such similar code.
--
The dead increasingly dominate and strangle both the living and the
not-yet born. Vampiric capital and undead corporate persons abuse
the lives and control the thoughts of homo faber. Ideas, once born,
become abortifacients against new conceptions.
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