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Re: Opinion on best practice...

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Date Thu, 7 Feb 2013 18:49:49 +1100
Subject Re: Opinion on best practice...
From Chris Angelico <rosuav@gmail.com>
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On Thu, Feb 7, 2013 at 5:50 PM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> On Thu, 07 Feb 2013 16:28:17 +1100, Chris Angelico wrote:
>
>> You misunderstand. It's actually a very simple rule. Python follows C's
>> principle of accepting that any return value from an expression should
>> be ignored if you don't do anything with it.
>
> Return values are safe. They don't do anything, since they are *being
> ignored*, not being executed as code. You have to explicitly choose to do
> something with the return value before it does anything.
>
> If C said "if you don't do anything with the return result of an
> expression, execute it as code in the shell", would you consider that a
> desirable principle to follow?
>
> def oh_my_stars_and_garters():
>     return "rm -rf /"
>
> oh_my_stars_and_garters()

Naming a function is safe, too.

def earth_shattering():
    os.system("rm -rf /")

earth_shattering;

But putting parentheses after it suddenly makes it dangerous. Wow!
Python's pretty risky, right?

In REXX, you simply don't *do* that sort of thing. (You'd use the CALL
statement, for instance.)

ChrisA

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Thread

Opinion on best practice... Anthony Correia <akcorreia@gmail.com> - 2013-02-04 20:14 -0800
  Re: Opinion on best practice... Michael Torrie <torriem@gmail.com> - 2013-02-04 23:04 -0700
  Re: Opinion on best practice... Terry Reedy <tjreedy@udel.edu> - 2013-02-05 02:56 -0500
    Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-05 13:23 +0000
  Re: Opinion on best practice... Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-02-05 08:56 +0100
    Re: Opinion on best practice... Peter Otten <__peter__@web.de> - 2013-02-05 11:35 +0100
      Re: Opinion on best practice... Ulrich Eckhardt <ulrich.eckhardt@dominolaser.com> - 2013-02-05 14:05 +0100
  Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-05 13:22 +0000
    Re: Opinion on best practice... Walter Hurry <walterhurry@lavabit.com> - 2013-02-05 21:01 +0000
      Re: Opinion on best practice... Neil Cerutti <neilc@norwich.edu> - 2013-02-05 21:39 +0000
        Re: Opinion on best practice... Ethan Furman <ethan@stoneleaf.us> - 2013-02-05 14:07 -0800
          Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-05 23:00 +0000
            Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-06 10:35 +1100
              Re: Opinion on best practice... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-06 12:55 +1100
                Re: Opinion on best practice... Dan Stromberg <drsalists@gmail.com> - 2013-02-05 18:14 -0800
                Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-06 17:16 +1100
                Re: Opinion on best practice... rusi <rustompmody@gmail.com> - 2013-02-05 23:32 -0800
                Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-06 15:18 +0000
                Re: Opinion on best practice... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-06 12:37 -0500
                Re: Opinion on best practice... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-07 10:46 +1100
                Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-07 16:28 +1100
                Re: Opinion on best practice... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-07 06:50 +0000
                Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-07 18:49 +1100
                Re: Opinion on best practice... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-08 09:49 +1100
                Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-08 17:54 +1100
                Re: Opinion on best practice... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-08 12:41 -0500
                Re: Opinion on best practice... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-07 13:54 -0500
                Re: Opinion on best practice... Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-02-08 09:58 +1100
                Re: Opinion on best practice... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-08 13:29 -0500
                Re: Opinion on best practice... Chris Angelico <rosuav@gmail.com> - 2013-02-09 11:28 +1100
                Re: Opinion on best practice... John Ladasky <john_ladasky@sbcglobal.net> - 2013-02-08 19:10 -0800
            Re: Opinion on best practice... Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-02-06 00:33 -0500
              Re: Opinion on best practice... Anssi Saari <as@sci.fi> - 2013-02-06 15:30 +0200
        Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-05 22:59 +0000
          Re: Opinion on best practice... Ian Kelly <ian.g.kelly@gmail.com> - 2013-02-05 17:05 -0700
            Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-06 15:04 +0000
          Re: Opinion on best practice... Neil Cerutti <neilc@norwich.edu> - 2013-02-06 14:20 +0000
            Re: Opinion on best practice... Grant Edwards <invalid@invalid.invalid> - 2013-02-06 15:11 +0000
      Re: Opinion on best practice... Nobody <nobody@nowhere.com> - 2013-02-06 03:32 +0000
        Re: Opinion on best practice... Michael Torrie <torriem@gmail.com> - 2013-02-05 22:07 -0700

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