Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Steven D'Aprano
On Mon, Jul 23, 2018 at 12:59:20AM +0200, Giampaolo Rodola' wrote: > You're back at "since we have X that justifies the addition of Y" [1] > and AFAICT that's the only argument you have provided so far in a 100+ > messages discussion. The PEP itself justifies the addition of Y. Chris' argument,

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Steven D'Aprano
On Sun, Jul 22, 2018 at 05:09:39PM +0200, Giampaolo Rodola' wrote: > > > I personally don't find "a ?? b" too bad (let's say I'm -0 about it) > > > but idioms such as "a?.b", "a ??= b" and "a?[3] ?? 4" look too > > > Perl-ish to me, non pythonic and overall not explicit, no matter what > > > the

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Steven D'Aprano
On Sun, Jul 22, 2018 at 11:26:15PM +1000, Chris Angelico wrote: > You forget that the operator will *short-circuit*. It will not > evaluate the second argument if the first argument is None. You cannot > do this with a function, other than with a hack like a lambda > function. We keep running up

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Mon, Jul 23, 2018 at 12:08 AM Chris Angelico wrote: > > On Mon, Jul 23, 2018 at 7:51 AM, Giampaolo Rodola' wrote: > > On Sun, Jul 22, 2018 at 10:55 PM Chris Angelico wrote: > >> > >> On Mon, Jul 23, 2018 at 6:43 AM, Giampaolo Rodola' > >> wrote: > >> > On Sun, Jul 22, 2018 at 10:01 PM

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Mon, Jul 23, 2018 at 7:51 AM, Giampaolo Rodola' wrote: > On Sun, Jul 22, 2018 at 10:55 PM Chris Angelico wrote: >> >> On Mon, Jul 23, 2018 at 6:43 AM, Giampaolo Rodola' >> wrote: >> > On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: >> >> >> >> On Mon, Jul 23, 2018 at 1:09 AM,

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 10:55 PM Chris Angelico wrote: > > On Mon, Jul 23, 2018 at 6:43 AM, Giampaolo Rodola' wrote: > > On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: > >> > >> On Mon, Jul 23, 2018 at 1:09 AM, Giampaolo Rodola' > >> wrote: > >> > On Sun, Jul 22, 2018 at 3:38 PM Chris

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 11:51 PM Giampaolo Rodola' wrote: > > On Sun, Jul 22, 2018 at 10:55 PM Chris Angelico wrote: > > > > On Mon, Jul 23, 2018 at 6:43 AM, Giampaolo Rodola' > > wrote: > > > On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: > > >> > > >> On Mon, Jul 23, 2018 at 1:09

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread David Mertz
On Sun, Jul 22, 2018, 4:56 PM Chris Angelico wrote: > It means people place crazily high demands on new proposals. > I think the bar has been much too low for introducing new features over the last 5 years or so. Internal changes like the new dictionary implementation are fine, but user-facing

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Antoine Pitrou
On Mon, 23 Jul 2018 06:53:53 +1000 Chris Angelico wrote: > > >> Which is back to what Steven said: people demand such a high > >> bar for new syntax that few existing pieces of syntax would pass it. > > > > Probably. That's what happens when a language is mature. Personally I > > don't think

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Peter J. Holzer
On 2018-07-22 10:33:23 -0700, Michael Selik wrote: > On Sat, Jul 21, 2018, 6:55 PM Steven D'Aprano wrote: > On Sun, Jul 22, 2018 at 01:56:35AM +0200, Giampaolo Rodola' wrote: > > On Thu, Jul 19, 2018 at 3:39 PM Steven D'Aprano > > wrote: > > > Tens of thousands of non-English

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Mon, Jul 23, 2018 at 6:43 AM, Giampaolo Rodola' wrote: > On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: >> >> On Mon, Jul 23, 2018 at 1:09 AM, Giampaolo Rodola' >> wrote: >> > On Sun, Jul 22, 2018 at 3:38 PM Chris Angelico wrote: >> > I find it less explicit mainly because it does

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Antoine Pitrou
On Sun, 22 Jul 2018 22:43:15 +0200 "Giampaolo Rodola'" wrote: > On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: > > > > On Mon, Jul 23, 2018 at 1:09 AM, Giampaolo Rodola' > > wrote: > > > On Sun, Jul 22, 2018 at 3:38 PM Chris Angelico wrote: > > > I find it less explicit mainly

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 10:01 PM Chris Angelico wrote: > > On Mon, Jul 23, 2018 at 1:09 AM, Giampaolo Rodola' wrote: > > On Sun, Jul 22, 2018 at 3:38 PM Chris Angelico wrote: > > I find it less explicit mainly because it does 3 things at once: check > > if attribute is None, use it if it's not

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Mon, Jul 23, 2018 at 1:09 AM, Giampaolo Rodola' wrote: > On Sun, Jul 22, 2018 at 3:38 PM Chris Angelico wrote: >> >> On Sun, Jul 22, 2018 at 11:35 PM, Giampaolo Rodola' >> wrote: >> > On Sun, Jul 22, 2018 at 2:10 PM Steven D'Aprano >> > wrote: >> >> >> >> On Sun, Jul 22, 2018 at

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Clément Pit-Claudel
On 2018-07-22 08:10, Steven D'Aprano wrote: > Indeed. And I think we ought to think carefully about the benefits and > costs of all of those variants separately. > > To me, the ?? operator seems like a clear and obvious win. The other > variants are more complex and the benefit is not as

Re: [Python-ideas] slice[] to get more complex slices

2018-07-22 Thread Serhiy Storchaka
22.07.18 22:03, Todd пише: For basic slices, the normal "slice(start, stop, step)" syntax works well.  But it becomes much more verbose to create more complicated slices that you want to re-use for multiple multidimensional data structures, like numpy, pandas, xarray, etc. One idea I had was

Re: [Python-ideas] slice[] to get more complex slices

2018-07-22 Thread Stefan Behnel
Todd schrieb am 22.07.2018 um 21:03: > For basic slices, the normal "slice(start, stop, step)" syntax works well. > But it becomes much more verbose to create more complicated slices that you > want to re-use for multiple multidimensional data structures, like numpy, > pandas, xarray, etc. > >

[Python-ideas] slice[] to get more complex slices

2018-07-22 Thread Todd
For basic slices, the normal "slice(start, stop, step)" syntax works well. But it becomes much more verbose to create more complicated slices that you want to re-use for multiple multidimensional data structures, like numpy, pandas, xarray, etc. One idea I had was to allow creating slices by

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Michael Selik
On Sat, Jul 21, 2018, 6:55 PM Steven D'Aprano wrote: > On Sun, Jul 22, 2018 at 01:56:35AM +0200, Giampaolo Rodola' wrote: > > On Thu, Jul 19, 2018 at 3:39 PM Steven D'Aprano > wrote: > > > Tens of thousands of non-English speakers have had to learn the meaning > > > of what might as well be

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Peter J. Holzer
On 2018-07-22 09:01:58 -0400, David Mertz wrote: > On Sun, Jul 22, 2018, 8:11 AM Steven D'Aprano wrote: > To me, the ?? operator seems like a clear and obvious win. The other > variants are more complex and the benefit is not as obvious to me, so I > haven't decided where I stand on

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 3:38 PM Chris Angelico wrote: > > On Sun, Jul 22, 2018 at 11:35 PM, Giampaolo Rodola' > wrote: > > On Sun, Jul 22, 2018 at 2:10 PM Steven D'Aprano wrote: > >> > >> On Sun, Jul 22, 2018 at 12:13:04PM +0200, Giampaolo Rodola' wrote: > >> > On Sun, Jul 22, 2018 at 3:55 AM

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Stephen J. Turnbull
Steven D'Aprano writes: > In my opinion, writing > > expression if expression is None else default > > is the *opposite* of Pythonic, it is verbose and the DRY violation is > inelegant (as well as inefficient). I'd much rather use: > > expression ?? default Sure, if

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Grégory Lielens
Short circuit if the first argument is NOT None, I guess? ;-) Yes, so a short circuit is sometimes good. Not often imho, for a default triggered by None, but sometimes... In the case it is, do you want it to be hidden in an expression? Usually it would be better to draw attention, when the

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Sun, Jul 22, 2018 at 11:35 PM, Giampaolo Rodola' wrote: > On Sun, Jul 22, 2018 at 2:10 PM Steven D'Aprano wrote: >> >> On Sun, Jul 22, 2018 at 12:13:04PM +0200, Giampaolo Rodola' wrote: >> > On Sun, Jul 22, 2018 at 3:55 AM Steven D'Aprano >> > wrote: >> [...] >> > > I don't think that "+"

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 2:10 PM Steven D'Aprano wrote: > > On Sun, Jul 22, 2018 at 12:13:04PM +0200, Giampaolo Rodola' wrote: > > On Sun, Jul 22, 2018 at 3:55 AM Steven D'Aprano wrote: > [...] > > > I don't think that "+" is harder to read than > > >

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Sun, Jul 22, 2018 at 11:22 PM, Grégory Lielens wrote: > The ?? operator is probably the less scary one regarding legibility, and in > guessing (or remembering) what it exactly does... > Well, at least I think I understand what it does exactly, but if I'm not > wrong there, what it does is

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Grégory Lielens
The ?? operator is probably the less scary one regarding legibility, and in guessing (or remembering) what it exactly does... Well, at least I think I understand what it does exactly, but if I'm not wrong there, what it does is also quite simple and minimal. A function returning it's first

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Chris Angelico
On Sun, Jul 22, 2018 at 10:10 PM, Steven D'Aprano wrote: > As a community, we're risk-adverse. I understand why we should be > conservative in what we add to the language (once added, it cannot > easily be removed if it turns out to be a mistake) but on Python-Ideas > we regularly demand levels

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Steven D'Aprano
On Sun, Jul 22, 2018 at 12:13:04PM +0200, Giampaolo Rodola' wrote: > On Sun, Jul 22, 2018 at 3:55 AM Steven D'Aprano wrote: [...] > > I don't think that "+" is harder to read than > > "standard_mathematics_operators_numeric_addition" > > > Please let's drop the argument that + - * / = and ? are

[Python-ideas] Add function readbyte to asyncio.StreamReader

2018-07-22 Thread Jörn Heissler
Hello, I'm implementing a protocol where I need to read individual bytes until a condition is met (value & 0x80 == 0). My current approach is: value = (await reader.readexactly(1))[0] To speed this up, I propose that a new function is added to asyncio.StreamReader: value = await

[Python-ideas] Fwd: PEP 505: None-aware operators

2018-07-22 Thread Paul Moore
Aargh, I hate Google Groups with a vengeance. If people *have* to post from there, can they please change reply-to so that replies don't get messed up. Or is that not possible, and yet another way that GG is just broken? Paul -- Forwarded message -- From: Paul Moore Date: 22

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Grégory Lielens
Except that the third possibility is not possible...if a is None, a[2] will throw an exception... For now at least ;-) ___ Python-ideas mailing list Python-ideas@python.org https://mail.python.org/mailman/listinfo/python-ideas Code of Conduct:

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 12:26 PM Paul Moore wrote: > On 22 July 2018 at 11:13, Giampaolo Rodola' wrote: > > - "a?[2] ?? 3" means "index 2 of list a is picked up if a is not None, > else > > use 3" > > Actually, doesn't it mean > > if a is not None, pick up index 2 of the list. > If a is None,

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Paul Moore
On 22 July 2018 at 11:13, Giampaolo Rodola' wrote: > - "a?[2] ?? 3" means "index 2 of list a is picked up if a is not None, else > use 3" Actually, doesn't it mean if a is not None, pick up index 2 of the list. If a is None, OR IF a[2] IS NONE, then use 3. If a is None but a[2] is not None, use

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Giampaolo Rodola'
On Sun, Jul 22, 2018 at 3:55 AM Steven D'Aprano wrote: > Indeed we do. But we also say: > > - we say "+" instead of "add" > - we say "//" instead of "floor division" > - we say "**" instead of "exponentiation" > - we say "&" instead of "bitwise AND" > - we say "f( ... )" instead of "call f with

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Grégory Lielens
To get rid of the two other ( ?. And ?[] ), we could also define getitem and getattr for None to always return None...;-) I'm joking, although such an "absorbing" None may have been a good choice when None was introduced, and maybe a way to do an absorbing-None per-statement maybe nice...Nice

Re: [Python-ideas] PEP 505: None-aware operators

2018-07-22 Thread Paul Moore
On 22 July 2018 at 02:54, Steven D'Aprano wrote: > I'll admit that the number and variety of new operators gives me some > reason to pause, but for the simplest and most obvious case, the > proposed ?? operator, I think that the fears about readability are > grossly exaggerated. Certainly *my*