Sam Smith wrote:
Usage Scenario:
I am implementing a multi-level commandline program. On windows
platform similar to "net /?" command which in turn has "net use /?",
"net computer /?" etc commandlines.
Some of my commandlines share the same option-arg, but the default
value to be associated with each of them is different. In one of the
commandlines I was trying to detect if the user has specified the
option or not and if not assign a different value to the option.
I normally don't advocate code duplication, but in this case I'd either
specialcase
if specialcommandline:
parser.add_option(special option)
else:
parser.add_option(normal option)
or completely separate the parsers for the two differing scenarios.
Irrespective of the usage scenario, I believe that it is important to
give the module user the ability to find out whether an option has
been specified or not by the user.
Irrespective of the usage scenario - you can't be serious here.
Some suggestions:
* Maybe a method can be added to the option class, isSpecified()
which will return True if the option is found on commandline
and optparse has read it or False if the option is not found
on the commandline.
* Add ability to query the Values instance which is returned by
parse_args
My doubts not withstanding, here's how to achieve the desired (I think)
behaviour in a few lines - not tested beyond what you see as I will hardly
ever use it myself:
import sets
import optparse as op
class Values(op.Values):
def __init__(self, defaults):
op.Values.__init__(self, defaults)
self.specified = sets.Set([])
def __setattr__(self, name, value):
self.__dict__[name] = value
if hasattr(self, "specified"):
self.specified.add(name)
def test(args):
p = op.OptionParser()
p.add_option("-f", dest="filename", default="tmp.txt")
v = Values(p.defaults)
p.parse_args(args, v)
if "filename" in v.specified:
info = "specified:"
else:
info = "using default:"
print info, v.filename
test(["-f", "other.txt"])
test(["-f", "tmp.txt"])
test([])
Peter
