anything new on the ternary operator?
Tor
added to python. Haven't heard much about that since the vote was announced
for a couple of months ago. What's the best way to follow that dicussion?
Or are we just waiting for the developers to make their decision?
Sean Ross
http://www.europython.org/Talks/Slides/Slides_Guido_python_euro2003.ppt
Conditional Expressions
- Vote in March
- (if C: x else: y) won the vote
- But not by a landslide
- Now in Filibuster mode :)
- When in doubt, don't change it
- Competing forces:
- feature bloat
- handy feature
Bob Gailer
Last I heard it was killed by Guido, which makes me wonder why we spent so
much time discussing and voting. If he did not want it I wish he had killed
it at the start. I thought the vote was to determine the best choice, and I
was looking forward to having it.
<grumble>Makes me wonder about the whole PEP process. Why bother! </grumble>
Bob Gailer
bga...@alum.rpi.edu
303 442 2625
Aahz
Bob Gailer <bga...@alum.rpi.edu> wrote:
>At 10:59 PM 7/6/2003 +0200, Tor wrote:
>>
>>What's the current status on the ternary operator that may or may not
>>be added to python. Haven't heard much about that since the vote was
>>announced for a couple of months ago. What's the best way to follow
>>that dicussion? Or are we just waiting for the developers to make
>>their decision?
>
>Last I heard it was killed by Guido, which makes me wonder why we spent
>so much time discussing and voting. If he did not want it I wish he had
>killed it at the start. I thought the vote was to determine the best
>choice, and I was looking forward to having it.
Guido made clear before the vote that only a clear statement from the
community would drive the addition of the ternary operator. Given that
the vote did not present a clear result, he did what he said he'd do.
How's that a prbolem?
--
Aahz (aa...@pythoncraft.com) <*> http://www.pythoncraft.com/
"Not everything in life has a clue in front of it...." --JMS
Russell Reagan
> I was looking forward to having it.
"Sean Ross" <sr...@connectmail.carleton.ca> wrote
> - (if C: x else: y) won the vote
I'm still learning python, so don't flame too much :-)
What is superior about using the proposed ternary operator instead of using
the 'and' and 'or' operators to simulate inline logic?
Ben Finney
> What is superior about using the proposed ternary operator instead of
> using the 'and' and 'or' operators to simulate inline logic?
The "cond and expr1 or expr2" does not always function as expected for a
ternary if-then-else operator. The PEP for the ternary operator
explains:
"A common way to emulate an if-then-else expression is:
<condition> and <expression1> or <expression2>
However, this doesn't work the same way: it returns <expression2>
when <expression1> is false! See FAQ 4.16 for alternatives that
work -- however, they are pretty ugly and require much more effort
to understand."
<http://www.python.org/peps/pep-0308.html>
FAQ 4.16 is here:
<http://www.python.org/cgi-bin/faqw.py?req=show&file=faq04.016.htp>
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Erik Max Francis
> What is superior about using the proposed ternary operator instead of
> using
> the 'and' and 'or' operators to simulate inline logic?
Because the and/or technique doesn't quite work. Instead of rehashing
this topic again, I'd recommend you check out the PEP 308 on the
conditional operator which goes through all the details:
http://www.python.org/peps/pep-0308.html
--
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Peter Hansen
>
> Last I heard it was killed by Guido, which makes me wonder why we spent so
> much time discussing and voting. If he did not want it I wish he had killed
> it at the start. I thought the vote was to determine the best choice, and I
> was looking forward to having it.
>
> <grumble>Makes me wonder about the whole PEP process. Why bother! </grumble>
From the PEP (http://python.org/peps/pep-0308.html) :
This is the community's one chance: if this PEP is approved with a clear
majority, it will be implemented in Python 2.4. ... If the community can't
decide, the BDFL will reject the PEP.
Also, reading PEP 1 "PEP Purpose and Guidelines", I see nothing in there to
suggest that the process was not followed, and lots of things that point out
that the BDFL's ruling is still the only thing that matters, in the end.
Those dissenting will be required to start their own fork of Python, then
shot. ;-)
PEP 1 also answers your question about "why we spent so much time discussing
and voting"...
-Peter
Tim Peters
> Last I heard it was killed by Guido,
Confirmed (I asked him; he answered <wink>).
> which makes me wonder why we spent so much time discussing and voting.
If he had accepted it, people who were opposed to it may have wondered the
same thing. IOW, the specific outcome doesn't appear to have anything to do
with the gist of what you're saying, here or below.
> If he did not want it I wish he had killed it at the start.
Likewise, if he did want it, I wish he had accepted it at the start. But he
said at the start that he was neither opposed nor in favor, so neither form
of this conditional gets off the ground.
> I thought the vote was to determine the best choice, and I was looking
> forward to having it.
There were many creative interpretations of the vote counts, but none of
them showed the consensus Guido said at the start would be needed for
adoption.
> <grumble>Makes me wonder about the whole PEP process.
Voting isn't a normal part of the PEP process. This was the second vote in
Python's history. The first was to pick whether "i" or "j" would be used to
denote imaginary literals (another case where Guido had no preference). The
"i" camp still complains about that one too <0.9j wink>.
> Why bother! </grumble>
For you with perfect hindsight, or for Guido with perfect foresight, there
wouldn't have been any point. Given that the outcome wasn't known in
advance, there was some point at the time.
Andreas Jung
--On Montag, 7. Juli 2003 2:13 Uhr +0000 Russell Reagan <rre...@attbi.com>
wrote:
Please stop the discussion. The ternary operator is dead (which is a very
good thing)
because GvR made the decision.
-aj
Erik Max Francis
> Please stop the discussion. The ternary operator is dead (which is a
> very
> good thing)
> because GvR made the decision.
There's not much doubt that the conditional operator will not be making
it into Python in the future, but just because the BDFL has made a
decree (although a significantly delayed one), it's a little naive to
think that discussion of it will not continue. This clause was in the
PEP ("the subject better not come up again"), but I'm not sure how this
clause will really have much effect. Obviously no more PEPs on the
subject will be accepted, and needless to say it won't be considered by
the development team in the future, but it seems weird to suggest that
because a PEP came up, was (after many months) indirectly rejected in a
presentation (the PEP is not even updated to show its rejected status),
that all users are precluded from discussing in the future.
Mind you, such discussion will not be very constructive, but just
saying, "Welp, it's not going to be added, nobody talk about it ever
again" is not going to be very effective when new people come in all the
time and, one must admit, at least some segment of the user community
would have liked the feature.
--
Erik Max Francis && m...@alcyone.com && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \ I am a gentlemen: I live by robbing the poor.
\__/ George Bernard Shaw
Erik Max Francis
> Guido made clear before the vote that only a clear statement from the
> community would drive the addition of the ternary operator. Given
> that
> the vote did not present a clear result, he did what he said he'd do.
> How's that a prbolem?
Bob's phrasing of it was obviously overly confrontational, but I do find
it at least a little unfortunate that the final decision on PEP 308 only
came indirectly (meaning not as any form of widespread public
announcement, but rather as a side point in a presentation at a local
conference) and many months after the voting processes was resolved
(which was in February, if I recall correctly).
Even the PEP on the subject hasn't been updated, and only those who
attended his particular presentation in a particular conference have
found out this decision (which, of course, they communicated to us just
now). (Mind you, after months of silence about the issue, it's not like
the decision should at all be a surprise to anyone.)
There isn't a problem that PEPs and such voting processes are worthless
-- obviously the BDFL has the final say -- but perhaps it would have
been a little nicer to get an official position on the subject earlier.
Paul Rudin
> Guido made clear before the vote that only a clear statement
> from the community would drive the addition of the ternary
> operator. Given that the vote did not present a clear result,
> he did what he said he'd do. How's that a prbolem?
I don't know the details of this process; but personally I think a
ternary operator would be a very good thing - and don't care about the
syntax too much. Maybe the right think to vote on was simply a yes/no
to "Do you want a ternary operator?".
Maybe the problem is perhaps that disagreement over the competing
syntactical suggestions obscures the fact that a majority would prefer
to see some ternary operator rather than none?
Moshe Zadka
> Bob's phrasing of it was obviously overly confrontational, but I do find
> it at least a little unfortunate that the final decision on PEP 308 only
> came indirectly (meaning not as any form of widespread public
> announcement, but rather as a side point in a presentation at a local
> conference)
I'm sorry, I was going to let this slide by, but this comment made it
impossible. How the hell do you figure EuroPython, the biggest Python
conference in Europe and largely equivalent to the size of PyCon, is a
"local" conference?
By and large, I think EuroPython holds half the heritage of the venerable
IPCs, being way more international than PyCon. Announcements of new
developments are often done at conferences, especially the larger ones.
It has been said multiple times that Guido is likely to make an announcement
in EuroPython, and it was pretty easy to get the answer out on c.l.py soon
afterwards. While the PEP will eventually be updated, I am glad Guido thought
it was a higher priority to get 2.3b2 out the door in the little time he had
between EP and OSCON.
> There isn't a problem that PEPs and such voting processes are worthless
> -- obviously the BDFL has the final say -- but perhaps it would have
> been a little nicer to get an official position on the subject earlier.
Guido said that he wanted to let the discussion simmer down before he made
an official pronouncement. He also *did* consider the vote: if you remember,
there were a few interpretations. Guido chose the one who enforced
Condorset(sp?) semantics on the results, an arguably sane position considering
other free software projects use this voting method. According to this
interpretation, the vote resulted in "don't change".
--
Moshe Zadka -- http://moshez.org/
Buffy: I don't like you hanging out with someone that... short.
Riley: Yeah, a lot of young people nowadays are experimenting with shortness.
Agile Programming Language -- http://www.python.org/
Peter Hansen
>
> Mind you, such discussion will not be very constructive, but just
> saying, "Welp, it's not going to be added, nobody talk about it ever
> again" is not going to be very effective when new people come in all the
> time and, one must admit, at least some segment of the user community
> would have liked the feature.
At least by then the FAQ will be updated to point to the updated PEP,
which will, as originally intended, clearly explain the background,
the discussion, the vote, and the "final" decision.
-Peter
Aahz
>it at least a little unfortunate that the final decision on PEP 308 only
>came indirectly (meaning not as any form of widespread public
>announcement, but rather as a side point in a presentation at a local
>conference) and many months after the voting processes was resolved
>(which was in February, if I recall correctly).
That I'll agree with enthusiastically.
Aahz
Paul Rudin <paul_...@scientia.com> wrote:
>
>I don't know the details of this process; but personally I think a
>ternary operator would be a very good thing - and don't care about the
>syntax too much. Maybe the right think to vote on was simply a yes/no
>to "Do you want a ternary operator?".
Nope. Many people who were in favor of a ternary operator were entirely
opposed to specific variants; that's even more true of people who were
neutral on the subject.
Bob Gailer
The ternary op
if a: b else: y
would implement
if a:result = b
else: result = c
which is not identical to
result = a and b or c
John Hunter
Tim> There were many creative interpretations of the vote counts,
Tim> but none of them showed the consensus Guido said at the start
Tim> would be needed for adoption.
Perhaps there is a lesson for the next time a vote count comes around.
Although there wasn't a consensus on the syntactical form of a ternary
operator, there may be a consensus for the existence of one. This
suggests a runoff step is needed
Vote 1
0) choice 0
1) choice 1
...
N-1) choice N-1
N) No ternary operator
Vote 2 if sum(votes[:N])>votes[-1]
0) winner of vote 1
1) No ternary operator
I suspect many of not most of those who voted for some syntax of
ternary operator would prefer the first choice of the vote rather than
no choice, even if their pet candidate didn't win. Perhaps the python
community couldn't stand being dragged through a 2-tiered voting
procedure, but it looks like a fairer test.
John Hunter
Lulu of the Lotus-Eaters
|I'm sorry, I was going to let this slide by, but this comment made it
|impossible. How the hell do you figure EuroPython, the biggest Python
|conference in Europe and largely equivalent to the size of PyCon, is a
|"local" conference?
Yeah, but Donald Rumsfeld has let us 'merkins know that Old Europe is
now irrelevant. What could be more clear?
--
mertz@ | The specter of free information is haunting the `Net! All the
gnosis | powers of IP- and crypto-tyranny have entered into an unholy
.cx | alliance...ideas have nothing to lose but their chains. Unite
| against "intellectual property" and anti-privacy regimes!
-------------------------------------------------------------------------
Grant Edwards
>>>>>> "Tim" == Tim Peters <tim...@comcast.net> writes:
>
> Tim> There were many creative interpretations of the vote counts,
> Tim> but none of them showed the consensus Guido said at the start
> Tim> would be needed for adoption.
>
> Perhaps there is a lesson for the next time a vote count comes around.
> Although there wasn't a consensus on the syntactical form of a ternary
> operator, there may be a consensus for the existence of one. This
> suggests a runoff step is needed
Holy cow, didn't you notice the endless threads on voting
methods? There were two votes, both of which had various
"instant runoff" sort of features.
--
Grant Edwards grante Yow! Catsup and Mustard
at all over the place! It's
visi.com the Human Hamburger!
Moshe Zadka
|I'm sorry, I was going to let this slide by, but this comment made it
|impossible. How the hell do you figure EuroPython, the biggest Python
|conference in Europe and largely equivalent to the size of PyCon, is a
|"local" conference?
> Yeah, but Donald Rumsfeld has let us 'merkins know that Old Europe is
> now irrelevant. What could be more clear?
Well, to be quite honest, there were some "New Europe" attendees. The
most excellent Lithuanians, and yours truly.
Andrew Dalke
> Well, to be quite honest, there were some "New Europe" attendees. The
> most excellent Lithuanians, and yours truly.
As well as some of us 'mericans. 6, if I interpreted the stats correctly.
Andrew
da...@dalkescientific.com
Erik Max Francis
> I'm sorry, I was going to let this slide by, but this comment made it
> impossible. How the hell do you figure EuroPython, the biggest Python
> conference in Europe and largely equivalent to the size of PyCon, is a
> "local" conference?
After I posted that, I figured someone would probably take exception to
that term in order to stir things up. "Local" was merely meant to mean
that it is located in a particular area on the planet Earth which it is
less convenient for certain other people to attend. Yes, of course
that's true for every possible choice of locations. It was not meant as
a slight. (And, to trump your next response, yes, I know you do not
hail from Europe.)
The point is the decision wasn't announced publicly, in this
list/newsgroup (which reaches a much wider audience of Python users,
wouldn't you say?) or on the python.org Web site (which reaches an even
wider audience); it was mentioned in one presentation in a conference.
If you didn't attend to the conference, or _did_ attend the conference
and didn't happen to attend his presentation, you wouldn't have heard
about it except indirectly, which is precisely what's happening for many
of us here.
After all, as I write this, the PEP _still_ has not been updated with
the decision.
> Guido said that he wanted to let the discussion simmer down before he
> made
> an official pronouncement.
Sure, but did it really take six months to mull it over?
--
Erik Max Francis && m...@alcyone.com && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \ We're here to preserve democracy, not to practice it.
\__/ Capt. Frank Rasmey
Moshe Zadka
> (And, to trump your next response, yes, I know you do not
> hail from Europe.)
Ah? Of course I'm from Europe.
[The consensus in EP was that Israel was in Europe]
Michael Hudson
> There's not much doubt that the conditional operator will not be making
> it into Python in the future, but just because the BDFL has made a
> decree (although a significantly delayed one), it's a little naive to
> think that discussion of it will not continue. This clause was in the
> PEP ("the subject better not come up again"), but I'm not sure how this
> clause will really have much effect.
Slightly astonishingly, this does really seem to work. Consider PEP 666.
Cheers,
M.
--
If I didn't have my part-time performance art income to help pay
the bills, I could never afford to support my programming
lifestyle. -- Jeff Bauer, 21 Apr 2000
Alia Khouri
> On Mon, 07 Jul 2003, Erik Max Francis <m...@alcyone.com> wrote:
>
> > (And, to trump your next response, yes, I know you do not
> > hail from Europe.)
>
> Ah? Of course I'm from Europe.
> [The consensus in EP was that Israel was in Europe]
Sorry, I am confused: isn't Israel in the Middle East?
Alia
Tor
Was this the winning syntax? I think I saw it somewhere without the
parentheses, in something written by GvR. This syntax would have been great
without the parentheses. A bit messy with them, especially when they really
don't add any readability, like this
return if C1: x elif C2: y else: z
Why are the parentheses neccessary (and are they really)?
Skip Montanaro
>> [The consensus in EP was that Israel was in Europe]
Alia> Sorry, I am confused: isn't Israel in the Middle East?
Sure, but what continent is the the Middle East in, Europe, Asia or Africa?
I had to make the same decision in Musi-Cal. I decided that Israel was part
of Europe. The decision wasn't entirely arbitrary. Most concert dates we
list for Asia are in Japan, Korea or Hong Kong. There are almost never any
African concert dates listed. Israel was close enough to Europe that it
made sense to group it there.
Skip
Peter Hansen
>
> (if C: x else: z)
>
> Was this the winning syntax?
> Why are the parentheses neccessary (and are they really)?
Please don't reopen the discussion here, without at first reading the
entire archive of the previous discussion. ;-)
-Peter
Alan Kennedy
> Sorry, I am confused: isn't Israel in the Middle East?
Well, I prefer to avoid the geopolitics, but it is worth noting that
Israel enters the Eurovision song contest every year :-)
And even wins occasionally! Although not all Israelis were happy with
the last Israeli winner, Dana International :-
http://news.bbc.co.uk/2/hi/special_report/1998/05/98/eurovision/90279.stm
http://www.jewishsf.com/bk980515/ettrans.htm
regards,
--
alan kennedy
-----------------------------------------------------
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email alan: http://xhaus.com/mailto/alan
Moshe Zadka
> Sure, but what continent is the the Middle East in, Europe, Asia or Africa?
> I had to make the same decision in Musi-Cal. I decided that Israel was part
> of Europe. The decision wasn't entirely arbitrary. Most concert dates we
> list for Asia are in Japan, Korea or Hong Kong. There are almost never any
> African concert dates listed. Israel was close enough to Europe that it
> made sense to group it there.
Of course, for a music thingy it makes double the sense -- we're on the
Eurovision, which may effect concert dates.
[Of course, some may think grouping the eurovision with music is worse
than grouping Israel with Europe :)]
Moshe Zadka
> And even wins occasionally! Although not all Israelis were happy with
> the last Israeli winner, Dana International
Well, not all the Israelis were happy when she *won*.
Everybody, of course, had a field day when she dropped the award when
Israel hosted the competition the next year...
Robin Becker
Montanaro <sk...@pobox.com> writes
classical authors, historians & geographers. Asia begins across the
Hellespont so asiatic Turkey, Iraq, Syria, Palestine are not in Europe
and neither is the Israeli territory. I suspect Israelis would prefer to
be in America so that they wouldn't have to take part in the Eurovision
song contest.
--
Robin Becker
Fredrik Lundh
> the Middle East is certainly not in Europe at least according to
> classical authors, historians & geographers.
but all mediterranean countries are, according to the ITU.
> I suspect Israelis would prefer to be in America so that they
> wouldn't have to take part in the Eurovision song contest.
if we'd known that you folks would end up this bitter, we would
have given you one point ;-)
</F>
Robin Becker
Lundh <fre...@pythonware.com> writes
.....
>if we'd known that you folks would end up this bitter, we would
>have given you one point ;-)
>
></F>
back in the dark ages, not getting any points is a high point in
Britain's Eurovision career. With any luck we can consign this awfulness
to the dustbin of history. Perhaps we can make Guantanamo part of Europe
and send it there for a quickie death sentence.
--
Robin Becker
Erik Max Francis
> (if C: x else: z)
>
> Was this the winning syntax?
Best way to answer this is to just read PEP 308:
http://www.python.org/peps/pep-0308.html
--
Erik Max Francis && m...@alcyone.com && http://www.alcyone.com/max/
__ San Jose, CA, USA && 37 20 N 121 53 W && &tSftDotIotE
/ \ To be adult is to be alone.
\__/ Jean Rostand
Mark Jackson
> the Middle East is certainly not in Europe at least according to
> classical authors, historians & geographers. Asia begins across the
> Hellespont so asiatic Turkey, Iraq, Syria, Palestine are not in Europe
> and neither is the Israeli territory. I suspect Israelis would prefer to
> be in America so that they wouldn't have to take part in the Eurovision
> song contest.
I'm sure there must be an opt-out clause for Eurovision contests - I
certainly don't recall Israeli teams competing in It's a Knockout /
Jeux Sans Frontieres back in 1977.
On the other hand as part of America they might have gotten roped into
Almost Anything Goes.
--
Mark Jackson - http://www.alumni.caltech.edu/~mjackson
It is necessary to be slightly underemployed if you want to
do something significant. - James D. Watson