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Re: Having both if() and for() statements in one liner

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On Tue, Sep 17, 2013 at 10:17 AM, Tim Chase
<python.list@tim.thechases.com>wrote:

> On 2013-09-17 16:21, Ferrous Cranus wrote:
> > I just want to say tot he program that
> >
> > that only run the for statement if and only if person=='George'
> >
> > I dont see nay reason as to why this fails
> >
> > perhaps like:
> >
> > for times in range(0, 5) if person=='George':
> >
> > but that fails too...
> > there must be written on soem way.
>
> The canonical way to do this is the obvious:
>
>   if person == "George":
>     for times in range(0, 5):
>       ...
>
> That said, you can do stupid things to abstract the logic like
>
>   def iterate_if(condition, iterable):
>     if condition:
>       for item in iterable:
>         yield item
>
> which you can use something like
>
>   for times in iterate_if(person == "George", range(0,5)):
>     ...
>
> but I don't advise it.  Mainly, because the iterable will be
> evaluated when passed as an argument, which incurs the runtime cost.
> In the canonical form, if the test isn't passed, the range(n,m) is
> never even evaluated.
>
> -tkc
>
>
> Tim, that's great! or in the wonderful world of Onslow, "Oh nice"
http://en.wikipedia.org/wiki/Onslow_(Keeping_Up_Appearances)


>
>
> --
> https://mail.python.org/mailman/listinfo/python-list
>



-- 
Joel Goldstick
http://joelgoldstick.com

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Thread

Having both if() and for() statements in one liner Ferrous Cranus <nikos.gr33k@gmail.com> - 2013-09-17 15:02 +0300
  Re: Having both if() and for() statements in one liner Robert Kern <robert.kern@gmail.com> - 2013-09-17 13:52 +0100
  Re: Having both if() and for() statements in one liner Roy Smith <roy@panix.com> - 2013-09-17 09:00 -0400
    Re: Having both if() and for() statements in one liner Ferrous Cranus <nikos.gr33k@gmail.com> - 2013-09-17 16:21 +0300
      Re: Having both if() and for() statements in one liner Heiko Wundram <modelnine@modelnine.org> - 2013-09-17 15:46 +0200
      Re: Having both if() and for() statements in one liner Tim Chase <python.list@tim.thechases.com> - 2013-09-17 09:17 -0500
      Re: Having both if() and for() statements in one liner Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-17 10:32 -0400
      Re: Having both if() and for() statements in one liner Dave Angel <davea@davea.name> - 2013-09-17 18:54 +0000
        Re: Having both if() and for() statements in one liner Steven D'Aprano <steve@pearwood.info> - 2013-09-18 02:10 +0000
          Re: Having both if() and for() statements in one liner Joshua Landau <joshua@landau.ws> - 2013-09-18 06:55 +0100
          Re: Having both if() and for() statements in one liner Chris Angelico <rosuav@gmail.com> - 2013-09-18 17:00 +1000
    Re: Having both if() and for() statements in one liner Chris Angelico <rosuav@gmail.com> - 2013-09-18 01:04 +1000
    Re: Having both if() and for() statements in one liner Joel Goldstick <joel.goldstick@gmail.com> - 2013-09-17 11:15 -0400

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