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Groups > comp.lang.python > #62548
| From | Ned Batchelder <ned@nedbatchelder.com> |
|---|---|
| Subject | Re: cascading python executions only if return code is 0 |
| Date | 2013-12-22 14:49 -0500 |
| References | <l97elv$etg$1@ger.gmane.org> <BAY176-W23B383D8FC920EE78C424DAC60@phx.gbl> |
| Newsgroups | comp.lang.python |
| Message-ID | <mailman.4506.1387741799.18130.python-list@python.org> (permalink) |
On 12/22/13 2:10 PM, Frank Cui wrote:
> sorry, but what if I need to have different parameters in these functions ?
Frank, welcome to the group. Common convention is to put your response
below the exiting message, so that the conversation continues down the page.
(See my answer below... :)
>
>
> > To: python-list@python.org
> > From: breamoreboy@yahoo.co.uk
> > Subject: Re: cascading python executions only if return code is 0
> > Date: Sun, 22 Dec 2013 19:31:21 +0000
> >
> > On 22/12/2013 19:17, Roy Smith wrote:
> > > In article <mailman.4500.1387739297.18130.python-list@python.org>,
> > > Frank Cui <ycui@outlook.com> wrote:
> > >
> > >> hey guys,
> > >> I have a requirement where I need to sequentially execute a bunch of
> > >> executions, each execution has a return code. the followed
> executions should
> > >> only be executed if the return code is 0. is there a cleaner or
> more pythonic
> > >> way to do this other than the following ?
> > >> if a() == 0: if b() == 0: c()
> > >> Thanks for your input.
> > >> frank
> > >
> > > Yup! Just do:
> > >
> > > a() or b() or c()
> > >
> > > The "or" operation has what's known as "short-circuit" semantics. That
> > > means, if the first operand is true, it doesn't evaluate the second
> > > operand. Just make sure that a(), b(), and c() all return something
> > > which is true if they succeed and false otherwise.
> > >
> >
> > Really? :)
> >
> > --
> > My fellow Pythonistas, ask not what our language can do for you, ask
> > what you can do for our language.
> >
> > Mark Lawrence
> >
> > --
> > https://mail.python.org/mailman/listinfo/python-list
>
>
The most Python-natural way to deal with your problem would be to have
these functions not return status codes at all. Instead, have them
raise an exception if something goes wrong. Then you can invoke them
most naturally:
a()
b()
c()
Execution will continue as long as no exceptions are raised. If you
need to deal with the failure case also, then:
try:
a()
b()
c()
except Exception as e:
# do something here
Depending on how you want to deal with failures, you'd probably use your
own subclass of Exception, but this is the general idea.
Return codes can be awkward, especially in Python which has exception
integrated so fully into the language, library, and culture.
--
Ned Batchelder, http://nedbatchelder.com
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cascading python executions only if return code is 0 Frank Cui <ycui@outlook.com> - 2013-12-22 15:37 -0300
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-22 14:17 -0500
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-22 19:31 +0000
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-22 15:05 -0500
Re: cascading python executions only if return code is 0 Cameron Simpson <cs@zip.com.au> - 2013-12-23 08:39 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-22 16:53 -0500
Re: cascading python executions only if return code is 0 Cameron Simpson <cs@zip.com.au> - 2013-12-23 09:11 +1100
Re: cascading python executions only if return code is 0 Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-12-22 22:10 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 14:22 +1100
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-23 03:43 +0000
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 14:45 +1100
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-23 03:54 +0000
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 14:59 +1100
RE: cascading python executions only if return code is 0 Frank Cui <ycui@outlook.com> - 2013-12-22 16:10 -0300
Re: cascading python executions only if return code is 0 Ned Batchelder <ned@nedbatchelder.com> - 2013-12-22 14:49 -0500
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-23 00:08 +0000
RE: cascading python executions only if return code is 0 Frank Cui <ycui@outlook.com> - 2013-12-22 16:35 -0300
Re: cascading python executions only if return code is 0 Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2013-12-23 13:30 +1300
Re: cascading python executions only if return code is 0 Rick Johnson <rantingrickjohnson@gmail.com> - 2013-12-22 14:27 -0800
RE: cascading python executions only if return code is 0 Frank Cui <ycui@outlook.com> - 2013-12-22 19:14 -0300
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 09:51 +1100
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-22 23:02 +0000
Re: cascading python executions only if return code is 0 Rick Johnson <rantingrickjohnson@gmail.com> - 2013-12-22 15:57 -0800
Re: cascading python executions only if return code is 0 Ned Batchelder <ned@nedbatchelder.com> - 2013-12-23 07:27 -0500
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-23 12:44 +0000
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-23 00:25 +0000
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-22 20:24 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 12:35 +1100
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-23 13:33 +1100
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 14:09 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-22 23:57 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-23 16:09 +1100
Re: cascading python executions only if return code is 0 Ethan Furman <ethan@stoneleaf.us> - 2013-12-23 04:45 -0800
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-23 10:10 -0500
Re: cascading python executions only if return code is 0 Ethan Furman <ethan@stoneleaf.us> - 2013-12-23 08:00 -0800
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-26 20:37 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-27 12:44 +1100
Re: cascading python executions only if return code is 0 Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-12-26 21:20 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-27 13:27 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-26 23:29 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-27 15:40 +1100
Re: cascading python executions only if return code is 0 Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-12-27 11:15 -0500
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-27 11:42 -0500
Re: cascading python executions only if return code is 0 Rustom Mody <rustompmody@gmail.com> - 2013-12-27 22:39 +0530
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-28 08:24 +1100
Re: cascading python executions only if return code is 0 pecore@pascolo.net - 2013-12-28 00:59 +0100
Re: cascading python executions only if return code is 0 Gene Heskett <gheskett@wdtv.com> - 2013-12-27 19:12 -0500
Re: cascading python executions only if return code is 0 Tim Chase <python.list@tim.thechases.com> - 2013-12-26 20:50 -0600
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-27 15:39 +1100
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-27 15:45 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-27 00:05 -0500
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-27 16:15 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-27 00:41 -0500
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-27 18:00 +0000
Re: cascading python executions only if return code is 0 Grant Edwards <invalid@invalid.invalid> - 2013-12-30 17:36 +0000
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-24 04:05 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-23 11:03 -0800
Re: cascading python executions only if return code is 0 Chris Angelico <rosuav@gmail.com> - 2013-12-24 06:12 +1100
RE: cascading python executions only if return code is 0 Nick Cash <nick.cash@npcinternational.com> - 2013-12-23 19:31 +0000
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-24 14:41 +1100
Re: cascading python executions only if return code is 0 Roy Smith <roy@panix.com> - 2013-12-23 22:58 -0500
Re: cascading python executions only if return code is 0 Peter Otten <__peter__@web.de> - 2013-12-23 18:45 +0100
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-23 13:20 +0000
Re: cascading python executions only if return code is 0 Ethan Furman <ethan@stoneleaf.us> - 2013-12-23 04:38 -0800
Re: cascading python executions only if return code is 0 Dennis Lee Bieber <wlfraed@ix.netcom.com> - 2013-12-23 10:12 -0500
Re: cascading python executions only if return code is 0 Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-12-24 04:13 +1100
Re: cascading python executions only if return code is 0 Mark Lawrence <breamoreboy@yahoo.co.uk> - 2013-12-23 15:22 +0000
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