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pythonoptparse
Daniel Delaney
Daniel Delaney

Reputation: 1183

Python Optparse list

I'm using the python optparse module in my program, and I'm having trouble finding an easy way to parse an option that contains a list of values.

For example:

--groups one,two,three.

I'd like to be able to access these values in a list format as options.groups[]. Is there an optparse option to convert comma separated values into a list? Or do I have to do this manually?

Upvotes: 40

Views: 27669

Answers (4)

Fengya Li
Fengya Li

Reputation: 4709

With optparse, to get a list value you can use action 'append':

from optparse import OptionParser
parser = OptionParser()
parser.add_option("--group",
                  action="append",
                  dest="my_groups")
(options, args) = parser.parse_args()
print options.my_groups

Then call your program like this:

$ python demo.py --group one --group two --group three

['one', 'two', 'three']

Upvotes: 10

S.Lott
S.Lott

Reputation: 392010

Look at option callbacks. Your callback function can parse the value into a list using a basic optarg.split(',')

Upvotes: 40

its me
its me

Reputation: 241

Again, just for the sake of archive completeness, expanding the example above:

  • You can still use "dest" to specify the option name for later access
  • Default values cannot be used in such cases (see explanation in Triggering callback on default value in optparse)
  • If you'd like to validate the input, OptionValueError should be thrown from foo_callback

The code (with tiny changes) would then be:

def get_comma_separated_args(option, opt, value, parser):
    setattr(parser.values, option.dest, value.split(','))

parser = OptionParser()
parser.add_option('-f', '--foo',
                  type='string',
                  action='callback',
                  callback=get_comma_separated_args,
                  dest = foo_args_list)

Upvotes: 12

Can Berk Güder
Can Berk Güder

Reputation: 113380

S.Lott's answer has already been accepted, but here's a code sample for the archives:

def foo_callback(option, opt, value, parser):
  setattr(parser.values, option.dest, value.split(','))

parser = OptionParser()
parser.add_option('-f', '--foo',
                  type='string',
                  action='callback',
                  callback=foo_callback)

Upvotes: 84

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