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Re: Opinion on best practice...

References (10 earlier) <5112eb4a$0$29965$c3e8da3$5496439d@news.astraweb.com> <mailman.1438.1360214905.2939.python-list@python.org> <51134e9f$0$21812$c3e8da3$76491128@news.astraweb.com> <mailman.1441.1360223398.2939.python-list@python.org> <51142f5e$0$6512$c3e8da3$5496439d@news.astraweb.com>
Date 2013-02-08 17:54 +1100
Subject Re: Opinion on best practice...
From Chris Angelico <rosuav@gmail.com>
Newsgroups comp.lang.python
Message-ID <mailman.1489.1360306481.2939.python-list@python.org> (permalink)

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On Fri, Feb 8, 2013 at 9:49 AM, Steven D'Aprano
<steve+comp.lang.python@pearwood.info> wrote:
> Chris Angelico wrote:
> Yes, that is correct. Because now you are executing code, which could do
> something, and some things are dangerous. But Python will never execute
> code unless you explicitly tell it to. There's no concept in Python of
> falling back onto code execution if parsing fails.

A bare expression IS explicitly calling for code execution. That's
simply the way the language is. If you don't want the return value to
be sent to the host, you either assign it to a variable, or use CALL
(if it's a function call).

> I note that you ignored my question. If REXX reaches code that fails to
> parse, does it send it to the shell to be executed by default? If the
> answer was No, I expect you would have said so.

Anything that doesn't parse is a syntax error. It's only expression
results that go to the host (shell).

> Good lord, that's even worse than I feared. So it's not just unparsable
> non-REXX code that is implicitly sent to the shell, but the equivalent to
> Python's NameErrors. And you can implicitly mix calls to the shell and REXX
> function calls in the same line.

If it was meant to be a name, then it'll be in an expression, which -
see above - is an explicit request for it to be handled by the host.
The only thing that'll trip you up there is misspelling a language
keyword:

iff blah blah blah blah

which will be sent to the host instead of being an 'IF' statement.

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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