[issue22049] argparse: type= doesn't honor nargs > 1
New submission from Chris Bruner: >From the documentation, I think that argparse should pass the entire >nargs-long string to the "type=" callable. Instead, it only passes the first >argument (of nargs), making it impossible within argparse's framework to check >for a tuple of mixed types, e.g., 2 ints and a float (my case), or a string >and three numbers, etc. See attached reproducer. -- files: argparse_typedef_bug.py messages: 223748 nosy: Chris.Bruner priority: normal severity: normal status: open title: argparse: type= doesn't honor nargs > 1 type: behavior versions: Python 2.7 Added file: http://bugs.python.org/file36048/argparse_typedef_bug.py ___ Python tracker <http://bugs.python.org/issue22049> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22050] argparse: read nargs > 1 options from file doesn't work
New submission from Chris Bruner:
When reading options from a file, argparse should read all values from
each line. Instead, it complains of there not being enough options.
python file:
#!/usr/bin/env python
import argparse
p = argparse.ArgumentParser(description='Reproduce argparse nargs file bug',
fromfile_prefix_chars='@')
p.add_argument('-t', '--triple', metavar='N', nargs=3)
args = p.parse_args(['@input.opts'])
print args
input.opts:
--triple 1 2 3
-t 2 2 32
Output:
bernoulli:myclu cwbrune$ argparse_nargs_file_bug.py
usage: argparse_nargs_file_bug.py [-h] [-t N N N]
argparse_nargs_file_bug.py: error: argument -t/--triple: expected 3 argument(s)
--
files: argparse_nargs_file_bug.py
messages: 223753
nosy: Chris.Bruner
priority: normal
severity: normal
status: open
title: argparse: read nargs > 1 options from file doesn't work
type: behavior
versions: Python 2.7
Added file: http://bugs.python.org/file36049/argparse_nargs_file_bug.py
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[issue22050] argparse: read nargs > 1 options from file doesn't work
Chris Bruner added the comment:
Tried the format you gave. Still doesn't work. Same error message:
bernoulli:myclu cwbrune$ argparse_nargs_file_bug.py
usage: argparse_nargs_file_bug.py [-h] [-t N N N]
argparse_nargs_file_bug.py: error: argument -t/--triple: expected 3 argument(s)
bernoulli:myclu cwbrune$ cat argparse_nargs_file_bug.py
#!/usr/bin/env python
import argparse
p = argparse.ArgumentParser(description='Reproduce argparse nargs file bug',
fromfile_prefix_chars='@')
p.add_argument('-t', '--triple', metavar='N', nargs=3)
args = p.parse_args(['@input.opts'])
print args
bernoulli:myclu cwbrune$ cat input.opts
--triple
1
2
3
-t
2
2
32
bernoulli:myclu cwbrune$
--
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[issue22050] argparse: read nargs > 1 options from file doesn't work
Chris Bruner added the comment: Oops, my mistake: had multiple '-t' in file, but not an "action=append". Your version works just fine. Sorry for the confusion, and thank you for the correction! -- ___ Python tracker <http://bugs.python.org/issue22050> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22049] argparse: type= doesn't honor nargs > 1
Chris Bruner added the comment: Yes, I know. My function just sees '1', but I think it should see '1 2 3' so that it can figure out what to do. That's impossible (well, impossible without saving state between calls) when it sees the arguments piecemeal. Sent from my iPhone > On Jul 24, 2014, at 9:42 PM, paul j3 wrote: > > > paul j3 added the comment: > > Note that > >'-t 1 2 3'.split() > > becomes > >['-t', '1', '2', '3'] > > Your 'type' function sees those 3 strings individually. Try printing > 'string' the first thing in your function to see what we mean. > > -- > nosy: +paul.j3 > > ___ > Python tracker > <http://bugs.python.org/issue22049> > ___ -- ___ Python tracker <http://bugs.python.org/issue22049> ___ ___ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue22049] argparse: type= doesn't honor nargs > 1
Chris Bruner added the comment:
Just had a chance to try this, and this does exactly what I wanted from
"type=". Thank you!
On Fri, Jul 25, 2014 at 4:17 PM, paul j3 wrote:
>
> paul j3 added the comment:
>
> What you want is a custom Action rather than a custom Type.
>
> from the documentation:
>
> >>> class FooAction(argparse.Action):
> ... def __call__(self, parser, namespace, values,
> option_string=None):
> ... print('%r %r %r' % (namespace, values, option_string))
> ... setattr(namespace, self.dest, values)
>
> 'values' will be the list ['1','2','3'], which you test and manipulate,
> before finally saving it to the 'namespace'.
>
> ret = (int(values[0]), int(values[1]), float(values[2]))
> setattr(namespace, self.dest, ret)
>
> Setting 'nargs=3' ensures that this action will always get a 3 item list.
> If the parser can't give it 3 items, it will raise an error rather than
> call your Action.
>
> 'optparse' passed the remaining argument strings to Option's callback,
> which could consume as many as it wanted. 'argparse' does not give the
> Actions that power. There is a fundamental difference in the parsing
> algorithm.
>
> --
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