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Re: Why is the argparse module so inflexible?

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From Terry Reedy <tjreedy@udel.edu>
Subject Re: Why is the argparse module so inflexible?
Date Sat, 29 Jun 2013 00:37:23 -0400
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On 6/29/2013 12:12 AM, rusi wrote:
> On Saturday, June 29, 2013 7:06:37 AM UTC+5:30, Ethan Furman wrote:
>> On 06/27/2013 03:49 PM, Steven D'Aprano wrote:
>>> [rant]
>>> I think it is lousy design for a framework like argparse to raise a
>>> custom ArgumentError in one part of the code, only to catch it elsewhere
>>> and call sys.exit. At the very least, that ought to be a config option,
>>> and off by default.
>>>
>>> Libraries should not call sys.exit, or raise SystemExit. Whether to quit
>>> or not is not the library's decision to make, that decision belongs to
>>> the application layer. Yes, the application could always catch
>>> SystemExit, but it shouldn't have to.
>>
>>
>> So a library that is explicitly designed to make command-line scripts easier
>> and friendlier should quit with a traceback?
>>
>> Really?
>
> So a library that behaves like an app is OK?

No, Steven is right as a general rule (do not raise SystemExit), but 
argparse was considered an exception because its purpose is to turn a 
module into an app. With the responses I have seen here, I agree that 
this is a bit short-sighted, as inflexible behavior. The tracker issue 
could use more review and comment.

-- 
Terry Jan Reedy

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Thread

Why is the argparse module so inflexible? Andrew Berg <robotsondrugs@gmail.com> - 2013-06-27 07:54 -0500
  Re: Why is the argparse module so inflexible? Roy Smith <roy@panix.com> - 2013-06-27 09:08 -0400
    Re: Why is the argparse module so inflexible? Andrew Berg <robotsondrugs@gmail.com> - 2013-06-27 08:49 -0500
    Re: Why is the argparse module so inflexible? Dave Angel <davea@davea.name> - 2013-06-27 12:02 -0400
      Re: Why is the argparse module so inflexible? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-27 22:49 +0000
        Re: Why is the argparse module so inflexible? Cameron Simpson <cs@zip.com.au> - 2013-06-28 09:34 +1000
        Re: Why is the argparse module so inflexible? Ethan Furman <ethan@stoneleaf.us> - 2013-06-28 18:36 -0700
          Re: Why is the argparse module so inflexible? rusi <rustompmody@gmail.com> - 2013-06-28 21:12 -0700
            Re: Why is the argparse module so inflexible? Terry Reedy <tjreedy@udel.edu> - 2013-06-29 00:37 -0400
              Re: Why is the argparse module so inflexible? Roy Smith <roy@panix.com> - 2013-06-29 10:12 -0400
                Re: Why is the argparse module so inflexible? Andrew Berg <robotsondrugs@gmail.com> - 2013-06-29 09:17 -0500
          Re: Why is the argparse module so inflexible? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-06-29 05:28 +0000
            Re: Why is the argparse module so inflexible? Marcin Szamotulski <mszamot@gmail.com> - 2013-06-29 13:38 +0100
            Re: Why is the argparse module so inflexible? MRAB <python@mrabarnett.plus.com> - 2013-06-29 16:58 +0100
            Re: Why is the argparse module so inflexible? Ethan Furman <ethan@stoneleaf.us> - 2013-06-29 12:17 -0700
        Re: Why is the argparse module so inflexible? Modulok <modulok@gmail.com> - 2013-06-28 19:39 -0600
        Re: Why is the argparse module so inflexible? Isaac To <isaac.to@gmail.com> - 2013-06-29 12:37 +0800
    Re: Why is the argparse module so inflexible? Robert Kern <robert.kern@gmail.com> - 2013-06-27 20:47 +0100

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