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[Python-Dev] PEP 389: argparse - new command line parsing module

Michael Foord fuzzyman at voidspace.org.uk
Sat Oct 3 17:17:36 CEST 2009 
Steven Bethard wrote:
> On Sat, Oct 3, 2009 at 3:45 AM, Yuvgoog Greenle <ubershmekel at gmail.com> wrote:
>   
>> I haven't checked if it's possible, but I suggest Argparse have it's
>> own exception class that inherits from SystemExit and that exception
>> would be thrown.
>>
>> ParseError, or something similar.
>>
>> I suggest this just because it would be more readable I guess and
>> would exactly explain why this code exits.
>>     
>
> I've never seen such an idiom before (subclassing SystemExit) but it
> would certainly be possible create an ArgumentParserExit exception
> like that. Then you would have your choice of overriding .exit() or
> catching the exception.
>
> Steve
>   
Why not just catch SystemExit? If you want a custom exception the 
overriding .exit() should be sufficient.

I'd be much more interested in Guido's suggestion of auto-generated 
custom help messages for sub-commands.

Michael

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