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

[Brett Cannon]

On Mon, Sep 28, 2009 at 20:44, "Martin v. Löwis" <martin at v.loewis.de> wrote:
>> Let's take ``getopt.getopt(sys.argv[1:], "a:b", ["alpha=", "beta"])``
>> as an example and simply assume that 'alpha' takes a string as an
>> argument and that it's required and that 'beta' is a boolean flag. To
>> pull everything out you could do::
>>
>>   options, args = getopt.getopt(sys.argv[1:], "a:b", ["alpha=", "beta"])
>>   options_dict = dict(options)
>>   alpha = options_dict.get('-a', options_dict.get('--alpha', ''))
>>   beta = '-b' in options_dict or '--beta' in options_dict
>>
>>   main(alpha, beta, args)
>>
>> Obviously if one of the getopt supporters has a better way of doing
>> this then please speak up.
>
> As Yuvgoog Greenle says, the canonical getopt way is to write
>
> alpha = None
> beta = False
> options, args = getopt.getopt(sys.argv[1:],"a:b",['alpha=','beta']):
> for opt, val in options:
>    if arg in ('-a','--alpha'):
>        alpha = val
>    elif arg in ('-b','--beta'):
>        beta = True
> main(alpha, beta, args)
>
> Even though this is many more lines, I prefer it over
> optparse/argparse: this code has only a single function call,
> whereas the argparse version has three function calls to remember.
> The actual processing uses standard Python data structures which
> I don't need to look up in the documentation.
>
>> Now, Steven, can you show how best to do this in argparse?
>
> This demonstrates my point: you were able to use getopt right away
> (even though not in the traditional way), whereas you need to ask
> for help on using argparse properly.
>

Actually, I had to read the docs for getopt. And I chose to not even
try argparse when the creator of the module is cc'ed on the email and
can obviously do a better example using his own code then I could.

-Brett