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Re: Supply condition in function call

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Date Wed, 25 Mar 2015 13:41:02 -0400
Subject Re: Supply condition in function call
From Joel Goldstick <joel.goldstick@gmail.com>
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On Wed, Mar 25, 2015 at 1:29 PM, Manuel Graune <manuel.graune@koeln.de> wrote:
> Hi,
>
> I'm looking for a way to supply a condition to an if-statement inside a
> function body when calling the function. I can sort of get what I want
> with using eval (see code below) but I would like to achieve this in a
> safer way. If there is a solution which is safer while being
> less flexible, that would be fine. Also, supplying the condition as a
> string is not necessary. What I want to do is basically like this:
>
> def test1(a, b, condition="True"):
>     for i,j in zip(a,b):
>         c=i+j
>         if eval(condition):
>            print("Foo")
>
I'm not sure I understand your question, but condition will evaluate
to True or False regardless, so:
         if condition:
            print ("Foo")
         else:
            print ("Bar")

eval can be dangerous as someone could put some unknown command with
side effects in condition

> test1([0,1,2,3],[1,2,3,4],"i+j >4")
> print("Bar")
> test1([0,1,2,3],[1,2,3,4],"c >4")
> print("Bar")
> test1([0,1,2,3],[1,2,3,4],"a[i] >2")
> print("Bar")
> test1([0,1,2,3],[1,2,3,4])
>
> Resulting in
>
> Foo
> Foo
> Bar
> Foo
> Foo
> Bar
> Foo
> Bar
> Foo
> Foo
> Foo
> Foo
>
> Thanks for your help
>
> Regards,
>
> Manuel
>
> --
> A hundred men did the rational thing. The sum of those rational choices was
> called panic. Neal Stephenson -- System of the world
> http://www.graune.org/GnuPG_pubkey.asc
> Key fingerprint = 1E44 9CBD DEE4 9E07 5E0A  5828 5476 7E92 2DB4 3C99
> --
> https://mail.python.org/mailman/listinfo/python-list



-- 
Joel Goldstick
http://joelgoldstick.com

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Thread

Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-25 18:29 +0100
  Re: Supply condition in function call Joel Goldstick <joel.goldstick@gmail.com> - 2015-03-25 13:41 -0400
    Re: Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-25 18:51 +0100
      Re: Supply condition in function call Joel Goldstick <joel.goldstick@gmail.com> - 2015-03-25 14:17 -0400
      Re: Supply condition in function call Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-25 12:22 -0600
      Re: Supply condition in function call Joel Goldstick <joel.goldstick@gmail.com> - 2015-03-25 14:42 -0400
  Re: Supply condition in function call Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-25 11:44 -0600
    Re: Supply condition in function call Grant Edwards <invalid@invalid.invalid> - 2015-03-25 19:53 +0000
      Re: Supply condition in function call Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-25 14:49 -0600
        Re: Supply condition in function call Grant Edwards <invalid@invalid.invalid> - 2015-03-26 15:41 +0000
  Re: Supply condition in function call Terry Reedy <tjreedy@udel.edu> - 2015-03-25 14:50 -0400
  Re: Supply condition in function call Gary Herron <gherron@digipen.edu> - 2015-03-25 12:13 -0700
    Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-25 21:02 -0700
      Re: Supply condition in function call Chris Angelico <rosuav@gmail.com> - 2015-03-26 17:00 +1100
        Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-26 18:41 -0700
          Re: Supply condition in function call Chris Angelico <rosuav@gmail.com> - 2015-03-27 12:56 +1100
            Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-26 19:21 -0700
              Re: Supply condition in function call Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-27 15:34 +1100
                Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-27 06:48 -0700
                Re: Supply condition in function call Chris Angelico <rosuav@gmail.com> - 2015-03-28 01:17 +1100
                Re: Supply condition in function call Mark Lawrence <breamoreboy@yahoo.co.uk> - 2015-03-27 16:00 +0000
                Re: Supply condition in function call Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-28 18:32 +1100
                Re: Supply condition in function call Chris Angelico <rosuav@gmail.com> - 2015-03-28 18:45 +1100
            Re: Supply condition in function call Larry Hudson <orgnut@yahoo.com> - 2015-03-27 17:26 -0700
              Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-27 18:27 -0700
              Re: Supply condition in function call Marko Rauhamaa <marko@pacujo.net> - 2015-03-28 09:50 +0200
                Re: Supply condition in function call Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-28 20:17 +1100
                Re: Supply condition in function call Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-28 03:19 -0600
                Re: Supply condition in function call Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2015-03-28 20:57 +1100
                Re: Supply condition in function call Cameron Simpson <cs@zip.com.au> - 2015-03-30 09:35 +1100
                Re: Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-30 00:46 +0200
          Re: Supply condition in function call Ian Kelly <ian.g.kelly@gmail.com> - 2015-03-26 20:25 -0600
            Re: Supply condition in function call Rustom Mody <rustompmody@gmail.com> - 2015-03-26 19:46 -0700
    Re: Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-26 07:27 +0100
      Re: Supply condition in function call Cameron Simpson <cs@zip.com.au> - 2015-03-26 18:06 +1100
        Re: Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-27 21:02 +0100
          Re: Supply condition in function call Cameron Simpson <cs@zip.com.au> - 2015-03-28 09:55 +1100
      Re: Supply condition in function call Peter Otten <__peter__@web.de> - 2015-03-26 10:03 +0100
        Re: Supply condition in function call Manuel Graune <manuel.graune@koeln.de> - 2015-03-27 20:46 +0100
          Re: Supply condition in function call Peter Otten <__peter__@web.de> - 2015-03-27 21:38 +0100
  Re: Supply condition in function call smap <askme.first@thankyouverymuch.invalid> - 2015-03-28 08:58 +0000

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