Hello, 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) 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. d = ${first, last, addr1, addr2, tel='123-456-789'} Keys should be valid identifier strings. Other keys raise SyntaxError. I wrote a simple POC implementation here. It looks working. https://github.com/atsuoishimoto/cpython/pull/2 (I prefer to use `j` for the prefix over `$`, but I may need to study the parser more to use an ASCII letter as token.)
Hi there! This request is a close cousin of the recent discussion about optional keywords arguments, which you can find in the archives at https://mail.python.org/archives/list/python-ideas@python.org/thread/MILIX6H... A lot of the same comments for and against apply here. I'll just cherry-pick a specific point: On 09/06/2020 14:45, Atsuo Ishimoto wrote:
Python is not Perl. By that I mean Python in general tends not to use non-alphanumeric symbols unless they already have a well established meaning (such as quote marks, arithmetic operators and so on). "${...}" definitely does not have such a meaning; a newcomer looking at the above would not have a lot of guidance as to what might be going on, and could be forgiven for thinking they were looking at some weird form of set. -- Rhodri James *-* Kynesim Ltd
Hi Thank you for comments 2020年6月10日(水) 0:11 Rhodri James <rhodri@kynesim.co.uk>:
Yeah, I don't think '${...}' is appearing, too. As I wrote, it was chosen for implementation reasons. I'm open for other syntax options. I'm curious what you think about another way to construct dictionaries.
I find this interesting, another solution would be for locals() to take arguments: dict(tel='1337-1337', **locals('name', 'surname'))
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,
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.
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!
On Wed, Jun 10, 2020 at 1:15 PM Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:
Be careful with this assumption. Python's dictionaries DO retain order, even if you can't easily talk about "the fifth element" [1], so anything that imposes requirements on the entry listed syntactically first may have consequences. ChrisA [1] which, as we all know, is Boron
Chris Angelico writes:
Thank you for the reminder! I did forget that point.
No requirements imposed! If iteration order matters and you want to take advantage of abbreviation, you might have to write d = {first : first, last, addr1, addr2, tel='123-456-789'} but frequently it would just work naturally: d = {first : first, last, addr1, addr2} Admittedly this distinction may be even more subtle than grit on Tim's screen, or randomizing the hash seed per process. And I suspect that people who want this feature will prefer the d{} notation for consistency inside the braces. Steve
Stephen J. Turnbull
d = {first : first, last, addr1, addr2}
I'm not a huge fan of this solution. It feels a bit like a hack instead of an intended syntax. Since prefixing characters on strings is already a thing, I lean more towards that solution. It's slightly easier to search (e.g. if the notation was d{literal1, literal2, etc}, one might search for "python d-dict"). However, If the above notation gains favor, perhaps it would be better to allow an empty ':' followed by a comma: d = {:, first, last, addr1, addr2} I don't much like the Perlyness of that syntax, but it's similar to using a prefix and it might lead to more explicit empty literals like {:} and {,} for dict and set respectively. I'm pretty sure that notation for empty literals has been discussed and rejected before, so I apologize if this brings up well-trodden ground. I'm pretty neutral on the proposal in general. It may also be possible to add a constructor to dict like: d = dict.from_locals('first', 'last', 'addr1', 'addr2') d['tel'] = '123-456-789' It might require a bit of stack inspection or some other magic, but it should be possible. It might be difficult for IDEs to recognize and hint and it might also be a blind-spot for re-factoring (if you change the name of a local variable). On Wed, Jun 10, 2020 at 3:06 AM Stephen J. Turnbull < turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:
I like Atsou's suggestion of omitting the key for literals: d = {:name, :addr, ’tel': '123-4567’} but using empty kwargs feels gross: d = dict(=name, =addr, tel='123-456') And this feels like it could easily lead to confusion: d = dict(name, addr, tell='123-456') On Thu, Jun 11, 2020 at 4:05 PM Abe Dillon <abedillon@gmail.com> wrote:
Hi Thank you for comments 2020年6月10日(水) 12:12 Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp>:
And in case of locals() is useful, the code may eventually become unsafe someday later.
I don't like it, either. But choice of valid letters are limited to such as “$", "'" and "?". So I think '$' is the best choice among these letters ;)
Also, please use dict display syntax (':' not '=').
Ah, this is a typo. I use ':' in my implementation.
'd{}' would be a nice choice.
It occurs to me there's an alternative syntax with even less notation:
d = {'tel' : '123-456-789', first, last, addr1, addr2}
This is acceptable, but I prefer prefixed dict better. Or, instead of prefixing a letter, we may be able to omit the key of items inside dict display. d = {:name, :addr, ’tel': '123-4567’} Thoughts?
instead of prefixing a letter, we may be able to omit the key of items inside dict display.
d = {:name, :addr, ’tel': '123-4567’}
This is my favorite variation on the notation so far. I'll give it a +1 On Wed, Jun 10, 2020 at 10:49 AM Atsuo Ishimoto <ishimoto@python.jp> wrote:
Hi there! This request is a close cousin of the recent discussion about optional keywords arguments, which you can find in the archives at https://mail.python.org/archives/list/python-ideas@python.org/thread/MILIX6H... A lot of the same comments for and against apply here. I'll just cherry-pick a specific point: On 09/06/2020 14:45, Atsuo Ishimoto wrote:
Python is not Perl. By that I mean Python in general tends not to use non-alphanumeric symbols unless they already have a well established meaning (such as quote marks, arithmetic operators and so on). "${...}" definitely does not have such a meaning; a newcomer looking at the above would not have a lot of guidance as to what might be going on, and could be forgiven for thinking they were looking at some weird form of set. -- Rhodri James *-* Kynesim Ltd
Hi Thank you for comments 2020年6月10日(水) 0:11 Rhodri James <rhodri@kynesim.co.uk>:
Yeah, I don't think '${...}' is appearing, too. As I wrote, it was chosen for implementation reasons. I'm open for other syntax options. I'm curious what you think about another way to construct dictionaries.
I find this interesting, another solution would be for locals() to take arguments: dict(tel='1337-1337', **locals('name', 'surname'))
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,
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.
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!
On Wed, Jun 10, 2020 at 1:15 PM Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:
Be careful with this assumption. Python's dictionaries DO retain order, even if you can't easily talk about "the fifth element" [1], so anything that imposes requirements on the entry listed syntactically first may have consequences. ChrisA [1] which, as we all know, is Boron
Chris Angelico writes:
Thank you for the reminder! I did forget that point.
No requirements imposed! If iteration order matters and you want to take advantage of abbreviation, you might have to write d = {first : first, last, addr1, addr2, tel='123-456-789'} but frequently it would just work naturally: d = {first : first, last, addr1, addr2} Admittedly this distinction may be even more subtle than grit on Tim's screen, or randomizing the hash seed per process. And I suspect that people who want this feature will prefer the d{} notation for consistency inside the braces. Steve
Stephen J. Turnbull
d = {first : first, last, addr1, addr2}
I'm not a huge fan of this solution. It feels a bit like a hack instead of an intended syntax. Since prefixing characters on strings is already a thing, I lean more towards that solution. It's slightly easier to search (e.g. if the notation was d{literal1, literal2, etc}, one might search for "python d-dict"). However, If the above notation gains favor, perhaps it would be better to allow an empty ':' followed by a comma: d = {:, first, last, addr1, addr2} I don't much like the Perlyness of that syntax, but it's similar to using a prefix and it might lead to more explicit empty literals like {:} and {,} for dict and set respectively. I'm pretty sure that notation for empty literals has been discussed and rejected before, so I apologize if this brings up well-trodden ground. I'm pretty neutral on the proposal in general. It may also be possible to add a constructor to dict like: d = dict.from_locals('first', 'last', 'addr1', 'addr2') d['tel'] = '123-456-789' It might require a bit of stack inspection or some other magic, but it should be possible. It might be difficult for IDEs to recognize and hint and it might also be a blind-spot for re-factoring (if you change the name of a local variable). On Wed, Jun 10, 2020 at 3:06 AM Stephen J. Turnbull < turnbull.stephen.fw@u.tsukuba.ac.jp> wrote:
I like Atsou's suggestion of omitting the key for literals: d = {:name, :addr, ’tel': '123-4567’} but using empty kwargs feels gross: d = dict(=name, =addr, tel='123-456') And this feels like it could easily lead to confusion: d = dict(name, addr, tell='123-456') On Thu, Jun 11, 2020 at 4:05 PM Abe Dillon <abedillon@gmail.com> wrote:
Hi Thank you for comments 2020年6月10日(水) 12:12 Stephen J. Turnbull <turnbull.stephen.fw@u.tsukuba.ac.jp>:
And in case of locals() is useful, the code may eventually become unsafe someday later.
I don't like it, either. But choice of valid letters are limited to such as “$", "'" and "?". So I think '$' is the best choice among these letters ;)
Also, please use dict display syntax (':' not '=').
Ah, this is a typo. I use ':' in my implementation.
'd{}' would be a nice choice.
It occurs to me there's an alternative syntax with even less notation:
d = {'tel' : '123-456-789', first, last, addr1, addr2}
This is acceptable, but I prefer prefixed dict better. Or, instead of prefixing a letter, we may be able to omit the key of items inside dict display. d = {:name, :addr, ’tel': '123-4567’} Thoughts?
instead of prefixing a letter, we may be able to omit the key of items inside dict display.
d = {:name, :addr, ’tel': '123-4567’}
This is my favorite variation on the notation so far. I'll give it a +1 On Wed, Jun 10, 2020 at 10:49 AM Atsuo Ishimoto <ishimoto@python.jp> wrote:
participants (7)
-
Abe Dillon -
Atsuo Ishimoto -
Chris Angelico -
J. Pic -
Rhodri James -
Robert DeLanghe -
Stephen J. Turnbull