> To: python-list@python.org > From: n...@nedbatchelder.com > Subject: Re: cascading python executions only if return code is 0 > Date: Sun, 22 Dec 2013 14:49:43 -0500 > > 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: breamore...@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-l...@python.org>, > > > > Frank Cui <y...@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 > > -- > https://mail.python.org/mailman/listinfo/python-list
Thanks for informing the rules.
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