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| From | Dennis Lee Bieber <wlfraed@ix.netcom.com> |
| Subject | Re: (test) ? a:b |
| Date | Sat, 25 Oct 2014 14:11:56 -0400 |
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On Sat, 25 Oct 2014 07:58:14 -0400, Ned Batchelder <ned@nedbatchelder.com>
declaimed the following:
>
>You mention "standard Python idioms." I think this style of
>conditional-via-indexing is becoming quite uncommon, and is no longer
>one of the standard Python idioms. This is now in the category of
>"outdated hack."
>
That may be true for the case where the index is based upon a Boolean
expression...
But the general form is still viable for either numeric indices (table
of functions) and switch/case style operations (replace the list with a
dictionary).
The Boolean application is merely a specialization of a more general
idiom.
The "true if cond else false" just doesn't fit my mind.
Even HP RPL (where one might expect strangeness) uses
if cond then true else false end
though being reverse polish overall, one could write
cond if then true else false end
as "if" merely starts the block, and it is the "then" which evaluates the
condition, whose value is still the top of stack at that point. I'm too
lazy to see if one could do
false true cond if then else end
which does have the problem of evaluating both false and true paths -- but
if no side-effects, might work: the "then" pulls the "cond", if true the
"else" takes the "true" and the "end" drops the "false" (and if "false" the
"else" drops the "true" and the "end" takes the "false")...
The more in-line form, usable outside of RPL appears as a function
ifte(cond, true, false)
which wasn't wanted for Python as it would evaluate both true and false (no
lazy evaluation; one would need to make a lambda for them)
--
Wulfraed Dennis Lee Bieber AF6VN
wlfraed@ix.netcom.com HTTP://wlfraed.home.netcom.com/
Back to comp.lang.python | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
(test) ? a:b "ast" <nomail@invalid.com> - 2014-10-22 10:29 +0200
Re: (test) ? a:b buscacio@gmail.com - 2014-10-22 02:05 -0700
Re: (test) ? a:b "ast" <nomail@invalid.com> - 2014-10-22 11:14 +0200
Re: (test) ? a:b Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-10-22 12:45 +0100
Re: (test) ? a:b "ast" <nomail@invalid.com> - 2014-10-27 09:01 +0100
Re: (test) ? a:b Michael Torrie <torriem@gmail.com> - 2014-10-22 11:16 -0600
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-23 11:44 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-22 20:15 +1100
Re: (test) ? a:b Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-10-22 10:16 +0100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-22 20:27 +1100
Re: (test) ? a:b Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-10-23 16:46 +1300
Re: (test) ? a:b MRAB <python@mrabarnett.plus.com> - 2014-10-23 11:12 +0100
Re: (test) ? a:b "ast" <nomail@invalid.com> - 2014-10-24 08:38 +0200
Re: (test) ? a:b Michael Torrie <torriem@gmail.com> - 2014-10-25 19:04 -0600
Re: (test) ? a:b Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2014-10-27 22:04 +1300
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-26 12:20 +1100
Re: (test) ? a:b Michael Torrie <torriem@gmail.com> - 2014-10-25 21:05 -0600
Re: (test) ? a:b Ned Batchelder <ned@nedbatchelder.com> - 2014-10-22 07:30 -0400
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-22 14:41 +0300
Re: (test) ? a:b Rustom Mody <rustompmody@gmail.com> - 2014-10-22 06:16 -0700
Re: (test) ? a:b "BartC" <bc@freeuk.com> - 2014-10-22 19:08 +0100
Re: (test) ? a:b Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-10-22 19:55 -0400
Re: (test) ? a:b "BartC" <bc@freeuk.com> - 2014-10-23 11:50 +0100
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-23 16:44 +0300
Re: (test) ? a:b Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-23 08:24 -0600
Re: (test) ? a:b Alain Ketterlin <alain@dpt-info.u-strasbg.fr> - 2014-10-23 16:41 +0200
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-23 19:20 +0300
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-24 19:38 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-24 19:45 +1100
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-24 12:37 +0300
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-25 00:07 +1100
Re: (test) ? a:b Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-24 12:22 -0600
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-24 21:46 +0300
Re: (test) ? a:b Dan Stromberg <drsalists@gmail.com> - 2014-10-24 10:20 -0700
Re: (test) ? a:b alister <alister.nospam.ware@ntlworld.com> - 2014-10-24 20:58 +0000
Re: (test) ? a:b Marko Rauhamaa <marko@pacujo.net> - 2014-10-25 00:02 +0300
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-25 16:03 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-25 16:25 +1100
Re: (test) ? a:b Ned Batchelder <ned@nedbatchelder.com> - 2014-10-25 07:58 -0400
Re: (test) ? a:b Ian Kelly <ian.g.kelly@gmail.com> - 2014-10-25 07:53 -0600
Re: (test) ? a:b Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2014-10-25 14:11 -0400
Re: (test) ? a:b alister <alister.nospam.ware@ntlworld.com> - 2014-10-25 19:49 +0000
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-26 07:45 +1100
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-26 11:10 +1100
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-26 12:03 +1100
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-26 15:15 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-26 15:34 +1100
Re: (test) ? a:b Terry Reedy <tjreedy@udel.edu> - 2014-10-26 17:12 -0400
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-27 11:38 +1100
Re: (test) ? a:b MRAB <python@mrabarnett.plus.com> - 2014-10-27 01:40 +0000
Re: (test) ? a:b Rustom Mody <rustompmody@gmail.com> - 2014-10-26 19:19 -0700
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-26 12:10 +1100
Re: (test) ? a:b Joshua Landau <joshua@landau.ws> - 2014-10-27 01:55 +0000
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-27 13:28 +1100
Re: (test) ? a:b Rustom Mody <rustompmody@gmail.com> - 2014-10-26 19:38 -0700
Re: (test) ? a:b Joshua Landau <joshua@landau.ws> - 2014-10-27 02:43 +0000
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-27 13:56 +1100
Re: (test) ? a:b Dan Stromberg <drsalists@gmail.com> - 2014-10-25 15:34 -0700
Re: (test) ? a:b Ben Finney <ben+python@benfinney.id.au> - 2014-10-26 10:53 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-26 11:01 +1100
Re: (test) ? a:b Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-10-26 01:09 +0100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-26 11:13 +1100
Re: (test) ? a:b Vito De Tullio <vito.detullio@gmail.com> - 2014-10-23 06:55 +0200
Re: (test) ? a:b Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2014-10-23 03:28 +1100
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-23 03:40 +1100
Re: (test) ? a:b alister <alister.nospam.ware@ntlworld.com> - 2014-10-22 18:03 +0000
Re: (test) ? a:b Matthew Ruffalo <mmr15@case.edu> - 2014-10-22 14:27 -0400
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-23 05:30 +1100
Re: (test) ? a:b Ned Batchelder <ned@nedbatchelder.com> - 2014-10-22 16:11 -0400
Re: (test) ? a:b Mark Lawrence <breamoreboy@yahoo.co.uk> - 2014-10-22 12:41 +0100
Re: (test) ? a:b alister <alister.nospam.ware@ntlworld.com> - 2014-10-22 15:12 +0000
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-23 02:18 +1100
Re: (test) ? a:b alister <alister.nospam.ware@ntlworld.com> - 2014-10-22 15:24 +0000
Re: (test) ? a:b Dan Stromberg <drsalists@gmail.com> - 2014-10-22 09:09 -0700
Re: (test) ? a:b Tobiah <toby@tobiah.org> - 2014-10-24 10:23 -0700
Re: (test) ? a:b Chris Angelico <rosuav@gmail.com> - 2014-10-25 04:27 +1100
Re: (test) ? a:b Tobiah <toby@tobiah.org> - 2014-10-24 11:31 -0700
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