getopt with negative numbers?

[Casey]

Is there an easy way to use getopt and still allow negative numbers as
args? I can easily write a workaround (pre-process the tail end of
the arguments, stripping off any non-options including negative
numbers into a separate sequence and ignore the (now empty) args list
returned by getopt, but it would seem this is such a common
requirement that there would be an option to treat a negative value as
an argument. Note that this is only a problem if the first non-option
is a negative value, since getopt stops processing options as soon as
it identifies the first argument value.

Alternatively, does optparse handle this? I haven't used optparse (I
know it is more powerful and OO, but you tend to stick with what you
know, especially when it is part of my normal python programming
template), but if it handles negative numbers I'm willing to learn it.

[Peter Otten]

Casey wrote:

Is there an easy way to use getopt and still allow negative numbers as
args? I can easily write a workaround (pre-process the tail end of
the arguments, stripping off any non-options including negative
numbers into a separate sequence and ignore the (now empty) args list
returned by getopt, but it would seem this is such a common
requirement that there would be an option to treat a negative value as
an argument. Note that this is only a problem if the first non-option
is a negative value, since getopt stops processing options as soon as
it identifies the first argument value.

Alternatively, does optparse handle this? I haven't used optparse (I
know it is more powerful and OO, but you tend to stick with what you
know, especially when it is part of my normal python programming
template), but if it handles negative numbers I'm willing to learn it.

optparse can handle options with a negative int value; "--" can be used to
signal that no more options will follow:

>>import optparse
parser = optparse.Option Parser()
parser.add_op tion("-a", type="int")

<Option at 0xb7d6fd8c: -a>

>>options, args = parser.parse_ar gs(["-a", "-42", "--", "-123"])
options.a

-42

>>args

['-123']

Without the "--" arg you will get an error:

>>parser.parse_ args(["-123"])

Usage: [options]

: error: no such option: -1
$

Peter

[Casey]

On Sep 27, 1:34 pm, Peter Otten <__pete...@web. dewrote:

optparse can handle options with a negative int value; "--" can be used to
signal that no more options will follow:

Thanks, Peter. getopt supports the POSIX "--" end of options
indicator as well, but that seems a little less elegant than being
able to simply set a value that tells the parser "I don't use any
numeric values as options, and I want to allow negative values as
arguments". At the parser level implemening this would be trivial and
I frankly was hoping it had been implemented and it just wasn't
mentioned in the spares Python getopt library reference.

[Peter Otten]

Casey wrote:

On Sep 27, 1:34 pm, Peter Otten <__pete...@web. dewrote:

>optparse can handle options with a negative int value; "--" can be used
to signal that no more options will follow:

Thanks, Peter. getopt supports the POSIX "--" end of options indicator
as well, but that seems a little less elegant than being able to simply
set a value that tells the parser "I don't use any numeric values as
options, and I want to allow negative values as arguments". At the
parser level implemening this would be trivial and I frankly was hoping
it had been implemented and it just wasn't mentioned in the spares
Python getopt library reference.

After a quick glance into the getopt and optparse modules I fear that both
hardcode the "if it starts with '-' it must be an option" behaviour.

Peter

[J. Clifford Dyer]

If you can access the argument list manually, you could scan it for a negative integer, and then insert a '--' argument before that, if needed, before passing it to getopt/optparse. Then you wouldn't have to worry about it on the command line.

Cheers,
Cliff

On Thu, Sep 27, 2007 at 08:08:05PM +0200, Peter Otten wrote regarding Re: getopt with negative numbers?:

>
Casey wrote:

On Sep 27, 1:34 pm, Peter Otten <__pete...@web. dewrote:

optparse can handle options with a negative int value; "--" can be used
to signal that no more options will follow:

Thanks, Peter. getopt supports the POSIX "--" end of options indicator
as well, but that seems a little less elegant than being able to simply
set a value that tells the parser "I don't use any numeric values as
options, and I want to allow negative values as arguments". At the
parser level implemening this would be trivial and I frankly was hoping
it had been implemented and it just wasn't mentioned in the spares
Python getopt library reference.

After a quick glance into the getopt and optparse modules I fear that both
hardcode the "if it starts with '-' it must be an option" behaviour.

Peter
--
http://mail.python.org/mailman/listinfo/python-list

[Nanjundi]

On Sep 27, 1:34 pm, Peter Otten <__pete...@web. dewrote:
....

>args

['-123']

Without the "--" arg you will get an error:

>parser.parse_a rgs(["-123"])

Usage: [options]

: error: no such option: -1
$

Peter

Passing -a-123 works

>>options, args = parser.parse_ar gs(["-a-123"])
options.a

-123

-N

[Casey]

On Sep 27, 2:21 pm, "J. Clifford Dyer" <[e-mail] tar.orgwrote:

If you can access the argument list manually, you could scan it for a negative integer, and then insert a '--' argument before that,
if needed, before passing it to getopt/optparse. Then you wouldn't have to worry about it on the command line.

Cheers,
Cliff

Brilliant!

<code>
# Look for the first negative number (if any)
for i,arg in enumerate(sys.a rgv[1:]):
# stop if
if arg[0] != "-": break
# if a valid number is found insert a "--" string before it
which
# explicitly flags to getopt the end of options
try:
f = float(arg)
sys.argv.insert (i+1,"--")
break;
except ValueError:
pass
</code>

[Casey]

On Sep 27, 2:21 pm, "J. Clifford Dyer" <[e-mail] tar.orgwrote:

If you can access the argument list manually, you could scan it for a negative integer,
and then insert a '--' argument before that, if needed, before passing it to getopt/optparse.
Then you wouldn't have to worry about it on the command line.

Cheers,
Cliff

Brilliant!

# Look for the first negative number (if any)
for i,arg in enumerate(sys.a rgv[1:]):
# stop if a non-argument is detected
if arg[0] != "-": break
# if a valid number is found insert a "--" string before it which
# explicitly flags to getopt the end of options
try:
f = float(arg)
sys.argv.insert (i+1,"--")
break;
except ValueError:
pass

[Steven Bethard]

Casey wrote:

Is there an easy way to use getopt and still allow negative numbers as
args?

[snip]

Alternatively, does optparse handle this?

Peter Otten wrote:

optparse can handle options with a negative int value; "--" can be used to
signal that no more options will follow:

>>>import optparse
parser = optparse.Option Parser()
parser.add_o ption("-a", type="int")

<Option at 0xb7d6fd8c: -a>

>>>options, args = parser.parse_ar gs(["-a", "-42", "--", "-123"])
options.a

-42

>>>args

['-123']

In most cases, argparse (http://argparse.python-hosting.com/) supports
negative numbers right out of the box, with no need to use '--':

>>import argparse
parser = argparse.Argume ntParser()
parser.add_ar gument('-a', type=int)
parser.add_ar gument('b', type=int)
args = parser.parse_ar gs('-a -42 -123'.split())
args.a

-42

>>args.b

-123
STeVe

[Neal Becker]

Casey wrote:

On Sep 27, 2:21 pm, "J. Clifford Dyer" <[e-mail] tar.orgwrote:

>If you can access the argument list manually, you could scan it for a
negative integer, and then insert a '--' argument before that,
if needed, before passing it to getopt/optparse. Then you wouldn't have
to worry about it on the command line.

Cheers,
Cliff

Brilliant!

<code>
# Look for the first negative number (if any)
for i,arg in enumerate(sys.a rgv[1:]):
# stop if
if arg[0] != "-": break
# if a valid number is found insert a "--" string before it
which
# explicitly flags to getopt the end of options
try:
f = float(arg)
sys.argv.insert (i+1,"--")
break;
except ValueError:
pass
</code>

One person's "brilliant" is another's "kludge".