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Re: Case Statements

From BartC <bc@freeuk.com>
Newsgroups comp.lang.python
Subject Re: Case Statements
Date 2016-03-16 15:00 +0000
Organization A noiseless patient Spider
Message-ID <ncbs8o$jd5$1@dont-email.me> (permalink)
References (8 earlier) <mailman.191.1458126480.12893.python-list@python.org> <ncbf5e$uq4$1@dont-email.me> <87vb4md362.fsf@elektro.pacujo.net> <ncbkr7$kj3$1@dont-email.me> <87mvpycx48.fsf@elektro.pacujo.net>

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On 16/03/2016 14:31, Marko Rauhamaa wrote:
> BartC <bc@freeuk.com>:

>> Even Ruby has one.

>>   case
>>   when this
>>      ....
>>   when that

> That's a different topic.

Yes but, if Ruby has it, why shouldn't Python? (Aren't they rivals or 
something?)

>> which is exactly equivalent to if this... elif that... (when the tests
>> are ordered), with one difference:

> That is no different from a chained if/elif.

That's what I said, but it's an interesting, more symmetric alternative.

> Scheme has this:

>     (case (die10)
>       ((1 3 5 7 9)
>        => (lambda (n)
>             n))
>       (else
>        => (lambda (n)
>             (/ n 2))))
>
> which maps 1, 3, 5, 7 and 9 onto themselves but halves 2, 4, 6, 8 and
> 10.

I don't get this; what does the lambda do here? Why not just yield 
either n or n/2?

> As for a chained if/elif, Scheme as "cond:"

>     (cond
>      ((windy?)
>       (fly-kite))
>      ((shining? sun)
>       (go-out))
>      ((raining?)
>       (play-soccer))
>      (else
>       (read-book)))

Which is like my Ruby case example. Simple and to the point. (Not sure 
of the significance of ?)

-- 
Bartc

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Case Statements jj0gen0info@gmail.com - 2016-03-15 13:46 -0700
  Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-15 23:11 +0000
  Re: Case Statements jj0gen0info@gmail.com - 2016-03-15 16:47 -0700
    Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-15 23:58 +0000
    Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 00:51 +0000
      Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 01:05 +0000
  Re: Case Statements jj0gen0info@gmail.com - 2016-03-15 18:55 -0700
    Re: Case Statements "Mario R. Osorio" <nimbiotics@gmail.com> - 2016-03-15 21:06 -0700
      Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 10:34 +0000
        Re: Case Statements Steven D'Aprano <steve@pearwood.info> - 2016-03-16 23:56 +1100
    Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 04:26 +0000
      Re: Case Statements Christian Gollwitzer <auriocus@gmx.de> - 2016-03-16 09:13 +0100
        Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 08:47 +0000
        Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 11:16 +0200
        Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-16 10:35 +0100
        Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 09:51 +0000
          Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 19:41 +0000
            Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 22:30 +0000
        Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-16 11:52 +0100
        Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 11:07 +0000
          Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 11:16 +0000
            Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 11:33 +0000
            Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 14:21 +0200
              Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 12:53 +0000
                Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 16:31 +0200
                Re: Case Statements BartC <bc@freeuk.com> - 2016-03-16 15:00 +0000
                Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 19:07 +0200
              Re: Case Statements Rustom Mody <rustompmody@gmail.com> - 2016-03-20 01:01 -0700
                Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-20 08:29 +0000
        Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-16 14:38 +0100
        Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 14:02 +0000
        Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 21:27 +0200
          Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-17 09:22 +0100
            Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-17 10:57 +0200
              Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-17 10:12 +0100
        Re: Case Statements Steven D'Aprano <steve@pearwood.info> - 2016-03-17 11:19 +1100
          Re: Case Statements Steven D'Aprano <steve@pearwood.info> - 2016-03-17 12:54 +1100
            Re: Case Statements Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-03-17 18:45 +1300
              Re: Case Statements Chris Angelico <rosuav@gmail.com> - 2016-03-17 17:30 +1100
                Re: Case Statements Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2016-03-18 18:59 +1300
              Re: Case Statements Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2016-03-17 17:29 +1100
                Re: Case Statements Chris Angelico <rosuav@gmail.com> - 2016-03-17 17:48 +1100
                Re: Case Statements Steven D'Aprano <steve@pearwood.info> - 2016-03-17 21:53 +1100
                Re: Case Statements Chris Angelico <rosuav@gmail.com> - 2016-03-17 22:49 +1100
            Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-17 10:23 +0100
            Re: Case Statements Chris Angelico <rosuav@gmail.com> - 2016-03-17 20:55 +1100
          Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-17 09:36 +0100
        Re: Case Statements Antoon Pardon <antoon.pardon@rece.vub.ac.be> - 2016-03-17 09:38 +0100
  Re: Case Statements l0r0m0a0i0l@gmail.com - 2016-03-16 06:15 -0700
    Re: Case Statements Steven D'Aprano <steve@pearwood.info> - 2016-03-17 00:27 +1100
      Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 14:00 +0000
    Re: Case Statements Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-03-16 13:59 +0000
  Re: Case Statements l0r0m0a0i0l@gmail.com - 2016-03-16 07:21 -0700
    Re: Case Statements Marko Rauhamaa <marko@pacujo.net> - 2016-03-16 16:33 +0200

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