Re: [Python-ideas] How assignment should work with generators?

On 28/11/2017 23:15, Alon Snir wrote: > On Wed, Nov 29, 2017 at 5:46 AM, Alon Snir wrote: >> I would like to mention that the issue of assignment to a target list, is >> also relevant to the case of elementwise assignment to a mutable sequence >> (e.g. lists and arrays).

Re: [Python-ideas] How assignment should work with generators?

Brendan Barnwell wrote: That's an interesting analysis, but I don't think your view is really the right one. It *is* unpacking a suitcase, it's just that *if necessary* the suitcase is constructed just in time for you to unpack it. I don't think that's right. An iterator created from a

Re: [Python-ideas] How assignment should work with generators?

On 2017-11-29 20:43, Steven D'Aprano wrote: At the point that you are conjuring from thin air an invisible suitcase that is an exact clone of the original suitcase, in order to unpack the clone without disturbing the original, I think the metaphor is so far from the real-world unpacking of

Re: [Python-ideas] How assignment should work with generators?

On Wed, Nov 29, 2017 at 03:08:43PM -0800, Brendan Barnwell wrote: > On 2017-11-29 14:21, Greg Ewing wrote: > >On the other hand, some people seem to be interpreting > >the word "unpack" as in "unpack a suitcase", i.e. the > >suitcase is empty afterwards. But unpacking has never > >meant that in

Re: [Python-ideas] How assignment should work with generators?

On Thu, Nov 30, 2017 at 11:21:48AM +1300, Greg Ewing wrote: > It seems that many people think about unpacking rather > differently from the way I do. I think the difference > is procedural vs. declarative. > > To my way of thinking, something like > >a, b, c = x > > is a pattern-matching

Re: [Python-ideas] How assignment should work with generators?

On Thu, Nov 30, 2017 at 10:49:19AM +1300, Greg Ewing wrote: > C Anthony Risinger wrote: > >Is __len__ a viable option now that __length_hint__ has been identified > >for hints? > > No, I misremembered that feature, sorry. > > But I still don't like the idea of changing behaviour > depending on

Re: [Python-ideas] Add a dict with the attribute access capability

On Wed, Nov 29, 2017 at 10:52:51AM +0200, Serhiy Storchaka wrote: > In 3.7 I have removed an old-deprecated plistlib.Dict. [1] Actually it > already was deprecated when the plistlib module was added to the regular > stdlib in Python 2.6. > > This is a dict subclass which allows to access items

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

I, too, think that this is too special a case for a dedicated syntax but so far I prefer: x None-or y The meaning is more clear to me. None-or is like regular or except that y is evaluated only if x is None. On Thu, Nov 30, 2017 at 2:35 AM, MRAB wrote: > On

Re: [Python-ideas] Immutable dictionaries

On 29/11/2017 17:30, Asen Bozhilov wrote: This is my first post here. I have strong experience with JavaScript and I'm lucky that I could move forward to Python. What I miss in Python are immutable dictionaries. They are especially useful for configurations and call functions which expect

Re: [Python-ideas] Add a dict with the attribute access capability

On 29/11/2017 23:34, Chris Barker wrote: On Wed, Nov 29, 2017 at 12:52 AM, Serhiy Storchaka > wrote: This is a dict subclass which allows to access items as attributes. d = plistlib.Dict() d['a'] = 1 assert d.a == 1 d.b =

Re: [Python-ideas] Add a dict with the attribute access capability

On Wed, Nov 29, 2017 at 12:52 AM, Serhiy Storchaka wrote: > This is a dict subclass which allows to access items as attributes. > > d = plistlib.Dict() > d['a'] = 1 > assert d.a == 1 > d.b = 2 > assert d['b'] == 2 > > What do you think about reviving this type as general

Re: [Python-ideas] How assignment should work with generators?

On 2017-11-29 14:21, Greg Ewing wrote: C Anthony Risinger wrote: `a, b, ...` to me says "pull out a and b and throw away the rest"... > The mere presence of more characters (...) implies something else will *happen* to the remaining items, not that they will be skipped. It seems that

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 2017-11-29 21:27, Greg Ewing wrote: Nick Coghlan wrote: What about more English-like syntax: X or else Y The problem with constructs like this is that they look like they should mean the same thing as "X or Y". How about: x otherwise y It looks different enough from "or" that

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On Wed, Nov 29, 2017 at 06:49:14AM -0800, David Mertz wrote: > I didn't say no use case exists, but rather "too special case." And/or > shortcutting is great, but truthiness feels much more general than noneness > to me. Of course truthiness is much more general than Noneness -- and that's

Re: [Python-ideas] Repurpose `assert' into a general-purpose check

On 11/29/2017 08:31 PM, Barry Warsaw wrote: Nathan Schneider wrote: I think it would be interesting to investigate how assert statements are used in the wild. I can think of three kinds of uses: assert statements are also a form of executable documentation. It says something like "I think

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On Thu, Nov 30, 2017 at 8:56 AM, Stephan Houben wrote: > > > Op 29 nov. 2017 22:35 schreef "Greg Ewing" : > > > It would read better with some kind of pronoun in there: > >A if it is not None else C > > Hypercard's Hypertalk had a special

Re: [Python-ideas] How assignment should work with generators?

C Anthony Risinger wrote: `a, b, ...` to me says "pull out a and b and throw away the rest"... > The mere presence of more characters (...) implies something else will *happen* to the remaining items, not that they will be skipped. It seems that many people think about unpacking rather

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

Op 29 nov. 2017 22:35 schreef "Greg Ewing" : It would read better with some kind of pronoun in there: A if it is not None else C Hypercard's Hypertalk had a special variable "it" that worked sort of like that. I considered that, but there are two issues. 1.

Re: [Python-ideas] How assignment should work with generators?

C Anthony Risinger wrote: Is __len__ a viable option now that __length_hint__ has been identified for hints? No, I misremembered that feature, sorry. But I still don't like the idea of changing behaviour depending on whether the RHS "looks like" an iterator or not. I'm not sure how to

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

Stephan Houben wrote: A if is not None else C Reading that gives me the feeling that something in my brain has slipped a tooth. It would read better with some kind of pronoun in there: A if it is not None else C Hypercard's Hypertalk had a special variable "it" that worked sort of like

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

Stephan Houben wrote: X or else Y Sounds like a Python dialect for Mafia use. customer.repay(loan) or else apply(baseball_bat, customer.kneecaps) -- Greg ___ Python-ideas mailing list Python-ideas@python.org

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

Nick Coghlan wrote: What about more English-like syntax: X or else Y The problem with constructs like this is that they look like they should mean the same thing as "X or Y". How about: x otherwise y It looks different enough from "or" that you're not going to accidentally read it

Re: [Python-ideas] Add a dict with the attribute access capability

On 29 November 2017 at 20:11, Barry Warsaw wrote: > Serhiy Storchaka wrote: > > In 3.7 I have removed an old-deprecated plistlib.Dict. [1] Actually it > > already was deprecated when the plistlib module was added to the regular > > stdlib in Python 2.6. > > > > Raymond noticed

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

True enough. I remember the prior discussion, but didn't look up the PEP number. I know it's hard to revisit these ideas, but occasionally it works, especially if a nicer spelling is found (Barry proposed some a bit different than my ideas) On Nov 29, 2017 9:55 AM, "Eric V. Smith"

Re: [Python-ideas] Repurpose `assert' into a general-purpose check

Nathan Schneider wrote: > I think it would be interesting to investigate how assert statements are > used in the wild. I can think of three kinds of uses: assert statements are also a form of executable documentation. It says something like "I think the internal state of my code must be this

Re: [Python-ideas] Immutable dictionaries

David Mertz wrote: > https://www.python.org/dev/peps/pep-0416/ PEP 351 (also rejected) is related to this. -Barry ___ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct:

Re: [Python-ideas] generator vs iterator etc. (was: How assignment should work with generators?)

Steven D'Aprano writes: > > The two iterators have the same duck-type, the generator is different. > > How is the generator different? My bad, I got the comparison backward. The generator *is* different, but it's because the generator has *extra* public methods, not fewer. Sorry for the

Re: [Python-ideas] Immutable dictionaries

2017-11-29 18:30 GMT+01:00 Asen Bozhilov : > I'd like to propose also literaling syntax for immutable dictionaries. > > immutable_dict = ( > 'key1' : 'value1', > 'key2' : 'value2' > ) Since Python 3.3, you can write: vstinner@apu$ python3 Python 3.6.3 (default,

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On Nov 29, 2017, at 12:40, David Mertz wrote: > I think some syntax could be possible to only "catch" some exceptions and let > others propagate. Maybe: > >val = name.strip()[4:].upper() except (AttributeError, KeyError): -1 > > I don't really like throwing a colon in an

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

> On Nov 29, 2017, at 12:40 PM, David Mertz wrote: > > I like much of the thinking in Random's approach. But I still think None > isn't quite special enough to warrant it's own syntax. > > However, his '(or None: name.strip()[4:].upper())' makes me realize that what > is

Re: [Python-ideas] Logging Levels

Hi, IMHO the prior decision(s) are too conservative. Reading the bugs, we can see lots of folks reinventing the wheel with common use cases for no good reason. I also gave examples in the log4j, docs, and web apps world that these levels are recognized needs. An addition would represent a

Re: [Python-ideas] Add a dict with the attribute access capability

On Wed, Nov 29, 2017 at 7:21 AM, Daniel Moisset wrote: > As reference of prior art, there is https://pypi.python.org/pypi/munch in > PyPI > Box is also popular as it permits deeper nesting: https://pypi.python.org/pypi/python-box/ https://github.com/cdgriffith/Box

Re: [Python-ideas] Immutable dictionaries

On Wed, Nov 29, 2017, at 12:30, Asen Bozhilov wrote: > I would appreciate your opinions on the topic. Most interesting for me is > why they are not already part of the language? See the rejection notes at https://www.python.org/dev/peps/pep-0416/ ___

Re: [Python-ideas] Immutable dictionaries

https://www.python.org/dev/peps/pep-0416/ Also: https://pypi.python.org/pypi/frozendict On Wed, Nov 29, 2017 at 9:30 AM, Asen Bozhilov wrote: > This is my first post here. I have strong experience with JavaScript and > I'm lucky that I could move forward to Python. >

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

I like much of the thinking in Random's approach. But I still think None isn't quite special enough to warrant it's own syntax. However, his '(or None: name.strip()[4:].upper())' makes me realize that what is being asked in all the '?(', '?.', '?[' syntax ideas is a kind of ternary expression.

[Python-ideas] Immutable dictionaries

This is my first post here. I have strong experience with JavaScript and I'm lucky that I could move forward to Python. What I miss in Python are immutable dictionaries. They are especially useful for configurations and call functions which expect dictionary as argument. In my opinion they would

Re: [Python-ideas] Logging Levels

Hi, As mentioned, using logging everywhere has some advantages. It doesn't have to be added later on, and it avoided a decent fraction of the work porting to Python 3. Have found users tend to like the labeling of messages, from INFO to ERROR. We skip the time stamp on the console and send

Re: [Python-ideas] How assignment should work with generators?

On Mon, Nov 27, 2017 at 3:49 PM, Greg Ewing wrote: > C Anthony Risinger wrote: > >> * Perhaps existence of `__len__` should influence unpacking? There is a >> semantic difference (and typically a visual one too) between 1-to-1 >> matching a fixed-width

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

I didn't say no use case exists, but rather "too special case." And/or shortcutting is great, but truthiness feels much more general than noneness to me. But yes, 'first_non_none()" might have to address laziness in some manner, depending on the use case. Zero argument lambdas and expression

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On Wed, Nov 29, 2017 at 3:12 PM Serhiy Storchaka wrote: > 29.11.17 15:01, Stephan Houben пише: > > What about a more general: > > > > A if B else C > > > > which would allow > > > > A if is not None else C > > > > but also e.g. > > > > A if >= 1 else 0 > > This look the

Re: [Python-ideas] Add a dict with the attribute access capability

As reference of prior art, there is https://pypi.python.org/pypi/munch in PyPI On 29 November 2017 at 05:52, Serhiy Storchaka wrote: > In 3.7 I have removed an old-deprecated plistlib.Dict. [1] Actually it > already was deprecated when the plistlib module was added to the

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

29.11.17 15:01, Stephan Houben пише: What about a more general: A if B else C which would allow A if is not None else C but also e.g. A if >= 1 else 0 This look the most "natural" to me. I.e. the least "unnatural". If we even will introduce a new special syntax I will prefer this

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 29 November 2017 at 12:41, Nick Coghlan wrote: > On 29 November 2017 at 22:38, Stephan Houben wrote: >> What about more English-like syntax: >> >> X or else Y > > The problem with constructs like this is that they look like they > should mean the same

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

29.11.17 14:39, Nick Coghlan пише: "a if def else b" -> pronounced "a if defined, else b" I understand "a if defined, else b" as try: result = a except (NameError, AttributeError, LookupError): result = b The problem is that None is not undefined. This is a

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

What about a more general: A if B else C which would allow A if is not None else C but also e.g. A if >= 1 else 0 Stephan Op 29 nov. 2017 13:41 schreef "Nick Coghlan" : > On 29 November 2017 at 22:38, Stephan Houben wrote: > > What about more

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 29 November 2017 at 22:38, Stephan Houben wrote: > What about more English-like syntax: > > X or else Y The problem with constructs like this is that they look like they should mean the same thing as "X or Y". Cheers, Nick. -- Nick Coghlan | ncogh...@gmail.com |

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 29 November 2017 at 21:53, Serhiy Storchaka wrote: > 29.11.17 11:45, Steven D'Aprano пише: >> On Wed, Nov 29, 2017 at 09:14:12AM +0200, Serhiy Storchaka wrote: >>> What is the syntax of the ternary operator in these languages? >> >> All four use: >> >> condition ?

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

What about more English-like syntax: X or else Y E.g. cache.get(foo) or else expensive_call(foo) Stephan Op 29 nov. 2017 12:54 schreef "Serhiy Storchaka" : 29.11.17 11:45, Steven D'Aprano пише: On Wed, Nov 29, 2017 at 09:14:12AM +0200, Serhiy Storchaka wrote: > >>

Re: [Python-ideas] How assignment should work with generators?

On 28/11/17 23:15, Alon Snir wrote: On Wed, Nov 29, 2017 at 5:46 AM, Alon Snir wrote: I would like to mention that the issue of assignment to a target list, is also relevant to the case of elementwise assignment to a mutable sequence (e.g. lists and arrays). Here as

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

29.11.17 11:45, Steven D'Aprano пише: On Wed, Nov 29, 2017 at 09:14:12AM +0200, Serhiy Storchaka wrote: 29.11.17 08:08, Steven D'Aprano пише: Perl is hardly the only language with null-coalescing operators -- we might better describe ?? as being familiar to C#, PHP, Swift and Dart. That's two

Re: [Python-ideas] How assignment should work with generators?

On Wed, Nov 29, 2017 at 5:46 AM, Alon Snir wrote: > I would like to mention that the issue of assignment to a target list, is > also relevant to the case of elementwise assignment to a mutable sequence > (e.g. lists and arrays). Here as well, the rhs of the assignment

Re: [Python-ideas] Proposal: allow length_hint to specify infinite iterators

On Wed, 29 Nov 2017 09:39:57 +0200 Serhiy Storchaka wrote: > 29.11.17 03:34, Steven D'Aprano пише: > > This wastes the opportunity to fail fast on operations which cannot > > possibly succeed, e.g. list(count()) must eventually fail with > > MemoryError. Or worse: if the OS

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

בתאריך יום ד׳, 29 בנוב׳ 2017, 12:29, מאת Lele Gaifax ‏: > Kirill Balunov writes: > > > Since the proposed semantics is more similar to the idea of "or", may be > it > > is better to consider something like: > > > > timeout then local_timeout then

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

Kirill Balunov writes: > Since the proposed semantics is more similar to the idea of "or", may be it > is better to consider something like: > > timeout then local_timeout then global_timeout > > I do not know how much this is a frequent case to be worthy of a keyword.

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

בתאריך יום ד׳, 29 בנוב׳ 2017, 11:46, מאת Steven D'Aprano ‏< st...@pearwood.info>: > On Wed, Nov 29, 2017 at 09:14:12AM +0200, Serhiy Storchaka wrote: > > 29.11.17 08:08, Steven D'Aprano пише: > > >Perl is hardly the only language with null-coalescing operators -- we > > >might better describe ??

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On Wed, Nov 29, 2017 at 09:14:12AM +0200, Serhiy Storchaka wrote: > 29.11.17 08:08, Steven D'Aprano пише: > >Perl is hardly the only language with null-coalescing operators -- we > >might better describe ?? as being familiar to C#, PHP, Swift and Dart. > >That's two mature, well-known languages

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 29 November 2017 at 18:49, Kirill Balunov wrote: > 2017-11-29 11:14 GMT+03:00 Nick Coghlan : >> >> It's OK to say "the use case exists, but I still >> don't want that particular syntax for it in Python" (I'm personally >> inclined to agree with you

[Python-ideas] Add a dict with the attribute access capability

In 3.7 I have removed an old-deprecated plistlib.Dict. [1] Actually it already was deprecated when the plistlib module was added to the regular stdlib in Python 2.6. This is a dict subclass which allows to access items as attributes. d = plistlib.Dict() d['a'] = 1 assert d.a == 1 d.b = 2

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

2017-11-29 11:14 GMT+03:00 Nick Coghlan : > It's OK to say "the use case exists, but I still > don't want that particular syntax for it in Python" (I'm personally > inclined to agree with you on that front). It's not OK to try to claim > there are no use cases where the

Re: [Python-ideas] [Python-Dev] What's the status of PEP 505: None-aware operators?

On 29 November 2017 at 16:13, David Mertz wrote: > Strong -1 still from me. Too special case for syntax. Just write a function > 'first_non_none()' that can perfectly will handle the need. That's the equivalent of SQL's COALESCE, and it's insufficient for the same reason "and"