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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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Xref: csiph.com comp.lang.python:38336

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