Executive summary:
Dicts are unordered, so we can distinguish dict from set by the first
item (no new notation), and after that default identifiers to (name :
in-scope value) items. Also some notational bikeshedding.
Atsuo Ishimoto writes:
> It is sometimes tedious to write a dictionary in Python. For example,
> def register_user(first, last, addr1, addr2):
> d = {'first': first,
> 'last': last,
> 'addr1': addr1,
> 'addr2': addr2,
> 'tel': '123-456-789'}
>
> requests.post(URL, d)
In this particular case,
def register_user(first, last, addr1, addr2):
d = locals().copy() # .copy is unnecessary in this case,
# but note that the next line may
# pollute the locals
d['tel'] = '123-456-789'
requests.post(URL, d)
DTRTs. How often would locals() be usable in this way? Note: in the
case of requests, this might be a vulnerability, because the explicit
dict display would presumably include only relevant items, while
locals() might inherit private credentials from the arguments, which
need to be explicitly del'ed from d.
> The dict literal contains a lot of duplicated words and quotation
> marks. Using dict type looks nicer, but still verbose.
>
> d = dict(first=first,
> last=last,
> addr1=addr1,
> addr2=addr2,
> tel='123-456-789')
>
> With recent JavaScript, the same object can be written more easily.
>
> d = {first, last, addr1, addr2, tel='123-456-789'}
>
> How about adding similar syntax to Python? Like raw strings, we can
> add prefix letters such as '$' to the opening curly brace for the
> purpose.
I understand that this was done for ease of your POC implementatation,
and you prefer a letter. But I'd like to emphasize: Please don't use
$ for this. Among other things, it is both in appearance and
historically based on "S" for "set"!
Also, please use dict display syntax (':' not '=').
If you're going to use prefix characters, I suggest 'd' for "dict",
and maybe 's' for "set" as well (to allow the use case 's{}' for the
empty set, though that's not terribly useful vs. set(). I'm mostly
proposing it so I be the first to say "-1" on 's{}'. :-)
This proposal does make me a more sympathetic to such abbreviations.
I'm still at best +0 on it, though.
It occurs to me there's an alternative syntax with even less notation:
d = {'tel' : '123-456-789', first, last, addr1, addr2}
I.e, if the first member of the display is a dict item, it's a dict,
and the rest of the members default to key = name of identifier and
value = value of identifier. If 'tel' weren't a key in d you'd write
d = {'first' : first, last, addr1, addr2}
A little awkward, but in many cases you'll be adding information as
you did.
> I wrote a simple POC implementation here. It looks working.
Thank you!
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