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From: hiral on 8 Jun 2010 04:38
Hi,

I am using optparser to do following...

Command syntax:
myscript -o[exension] other_arguments
where; extension can be 'exe', 'txt', 'pdf', 'ppt' etc.


Now to parse this, I am doing following...

parser.add_option("-oexe', dest=exe_file...)
parser.add_option("-otxt', dest=txt_file...)
parser.add_option("-opdf', dest=pdf_file...)
parser.add_option("-oppt', dest=ppt_file...)

The above way is the most simple way to parser options.
Can you please suggest any other best way / optimized way to parse
these kind of options.

Thank you in advance.
From: Thomas Jollans on 8 Jun 2010 05:03
On 2010-06-08 10:38, hiral wrote:
> Hi,
>
> I am using optparser to do following...
>
> Command syntax:
> myscript -o[exension] other_arguments
> where; extension can be 'exe', 'txt', 'pdf', 'ppt' etc.
>
>
> Now to parse this, I am doing following...
>
> parser.add_option("-oexe', dest=exe_file...)
> parser.add_option("-otxt', dest=txt_file...)
> parser.add_option("-opdf', dest=pdf_file...)
> parser.add_option("-oppt', dest=ppt_file...)
>
The format of options you're using here is totally non-standard. Yes,
many programs traditionally use it, but it's incompatible to the usual
UNIX and GNU recommendations. I've never actually heard of optparser,
but I'd expect it to have the usual limitations: GNU getopt (distributed
with Python by the way), I'm using the example because I know it fairly
well, lets you use either "-o exe" or "--output-format=exe" (GNU-style
long option) here.

So I'd recommend you either live with "-o exe" and the like, or you'll
probably have to write your own option parsing routine, which shouldn't
be too difficult, but really isn't worth it IMHO.

-- Thomas
> The above way is the most simple way to parser options.
> Can you please suggest any other best way / optimized way to parse
> these kind of options.
>
> Thank you in advance.
>

From: Jean-Michel Pichavant on 8 Jun 2010 06:03
hiral wrote:
> Hi,
>
> I am using optparser to do following...
>
> Command syntax:
> myscript -o[exension] other_arguments
> where; extension can be 'exe', 'txt', 'pdf', 'ppt' etc.
>
>
> Now to parse this, I am doing following...
>
> parser.add_option("-oexe', dest=exe_file...)
> parser.add_option("-otxt', dest=txt_file...)
> parser.add_option("-opdf', dest=pdf_file...)
> parser.add_option("-oppt', dest=ppt_file...)
>
> The above way is the most simple way to parser options.
> Can you please suggest any other best way / optimized way to parse
> these kind of options.
>
> Thank you in advance.
>

Here's a solution:

import optparse

class Process:
PREFIX = 'dispatch_'
@staticmethod
def undef():
print 'unsupported file type'
@staticmethod
def dispatch_exe():
print 'Hello exe file !'

def dispatchFileType(option, opt, value, parser):
"""Called by the parser, -o option."""
# call the corresponding method in the process method
getattr(Process, Process.PREFIX + value, Process.undef)()


parser = optparse.OptionParser()
parser.add_option("-o", "--output-fileType", type="string",
action="callback", callback=dispatchFileType)

options, args = parser.parse_args()


Cheers,

JM




From: Ben Finney on 8 Jun 2010 06:15
hiral <hiralsmaillist(a)gmail.com> writes:

> Command syntax:
> myscript -o[exension] other_arguments
> where; extension can be 'exe', 'txt', 'pdf', 'ppt' etc.

It's more generally applicable to refer to that as a “suffix” for the
filename, and specify the full suffix including the full-stop ('.')
character.

What your example suggests is that you want to have an option, “-o”,
which takes an argument which is the output suffix. I'd prefer to also
have a long option with a descriptive name for the same purpose.

So here's my interpretation::

>>> import optparse
>>> parser = optparse.OptionParser()
>>> parser.add_option(
... "-o", "--output-suffix",
... dest='out_suffix', metavar="SUFFIX",
... help="Specify SUFFIX as the suffix of the output filename.")
<Option at 0xf78d4350: -o/--output-suffix>
>>> print parser.format_option_help()
Options:
-h, --help show this help message and exit
-o SUFFIX, --output-suffix=SUFFIX
Specify SUFFIX as the suffix of the output filename.

> Can you please suggest any other best way / optimized way to parse
> these kind of options.

For testing the above, I make use of the 'shlex' module to split a
command-line string into separate arguments as the OptionParser will
expect::

>>> import shlex

The OptionParser instance, as the help message above explains, allows
the usual ways of specifying an argument to that option::

>>> cmdline_args = shlex.split("fooprog -o .exe spam beans")
>>> (opts, args) = parser.parse_args(cmdline_args[1:])
>>> opts.out_suffix
'.exe'

>>> cmdline_args = shlex.split("fooprog -o.txt spam beans")
>>> (opts, args) = parser.parse_args(cmdline_args[1:])
>>> opts.out_suffix
'.txt'

>>> cmdline_args = shlex.split("fooprog --output-suffix .pdf spam beans")
>>> (opts, args) = parser.parse_args(cmdline_args[1:])
>>> opts.out_suffix
'.pdf'

>>> cmdline_args = shlex.split("fooprog --output-suffix=.ppt spam beans")
>>> (opts, args) = parser.parse_args(cmdline_args[1:])
>>> opts.out_suffix
'.ppt'

--
\ “I used to be a proofreader for a skywriting company.” —Steven |
`\ Wright |
_o__) |
Ben Finney
From: Michele Simionato on 8 Jun 2010 06:20
On Jun 8, 10:38 am, hiral <hiralsmaill...(a)gmail.com> wrote:
> Hi,
>
> I am using optparser to do following...
>
> Command syntax:
> myscript -o[exension] other_arguments
>     where; extension can be 'exe', 'txt', 'pdf', 'ppt' etc.
>
> Now to parse this, I am doing following...
>
> parser.add_option("-oexe', dest=exe_file...)
> parser.add_option("-otxt', dest=txt_file...)
> parser.add_option("-opdf', dest=pdf_file...)
> parser.add_option("-oppt', dest=ppt_file...)
>
> The above way is the most simple way to parser options.
> Can you please suggest any other best way / optimized way to parse
> these kind of options.
>
> Thank you in advance.

Use plac: http://pypi.python.org/pypi/plac
Here is an example:

import plac

EXTENSIONS = ('exe', 'txt', 'pdf', 'ppt')

@plac.annotations(
ext=('a valid extension', 'option', 'o', None, EXTENSIONS))
def main(ext, *args):
"Do something"

if __name__ == '__main__':
plac.call(main)

$ python myscript.py -h
usage: myscript.py [-h] [-o {exe,txt,pdf,ppt}] [args [args ...]]

Do something

positional arguments:
args

optional arguments:
-h, --help show this help message and exit
-o, --ext {exe,txt,pdf,ppt}
a valid extension

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