Re: Optparse and help formatting?

Tim Chase wrote:
I've been learning the ropes of the optparse module and have been
having some trouble getting the help to format the way I want.

I want to specify parts of an option's help as multiline.
However, the optparse formatter seems to eat newlines despite my
inability to find anything in optparse.py that does something
obvious like .replace("\n", " ") to eat the newlines I stick in
the help. It also seems to mung tabs. An example from my code:

parser.add_option("-x", "--extended",
action="callback",
callback=callback_test,
type="string", # required to get metavar to show in help
dest="test",
metavar="CONF",
help="a comma-separated list of options.\n"
"s=[YYYY]MMDD,n=NAME,c=COLOR\n"
"s,start=[YYYY]MMDD\n"
"\tstart day of period (default, current day)\n"
...
)

which would accept options that looked something like

test.py -x s=20070401,n=XR71,c=black

(my callback_test breaks apart parser.rargs[0] to deal with the
funky params).

However, when I display the help, its reformatting eats the
newlines in my help-string and strangely looks like it converts
my tabs to spaces.

Any hints on how to either work around the problem or fix it?

I guess this is just an optparse-y week on c.l.py. ;-) Ben Finney pointed you in the right direction for optparse.

If you care to try out argparse (http://argparse.python-hosting.com/) which has a similar API, it has a builtin RawTextHelpFormatter formatter class::

import argparse

def my_type(string):
# split string and turn it into appropriate object(s)
return 'foo(%s)' % string

parser = argparse.ArgumentParser(
formatter_class=argparse.RawTextHelpFormatter
)
parser.add_argument(
"-x", "--extended",
type=my_type, dest="test", metavar="CONF",
help="a comma-separated list of options.\n"
"s=[YYYY]MMDD,n=NAME,c=COLOR\n"
"s,start=[YYYY]MMDD\n"
"\tstart day of period (default, current day)\n"
)

args = parser.parse_args()
print args.test

This program will produce output like::

$ python script.py -x sdfsdfas
foo(sdfsdfas)

$ python script.py --help
usage: script.py [-h] [-x CONF]

optional arguments:
-h, --help show this help message and exit
-x CONF, --extended CONF
a comma-separated list of options.
s=[YYYY]MMDD,n=NAME,c=COLOR
s,start=[YYYY]MMDD
start day of period ...

HTH,

STeVe
.