From Newsgroup: comp.lang.python

Hi,

I am writing a program for the command-line which uses 'argsparse'. I
want to make some options mandatory by setting 'required=True', but
still allow the program to run with the option '--version' (which just
shows the version and then exits) even if the mandatory options are
missing.

Is there a standard way of doing this?

Cheers,

Loris
--
This signature is currently under constuction.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.lang.python

"Loris Bennett" <[email protected]> writes:

Hi,

I am writing a program for the command-line which uses 'argsparse'. I
want to make some options mandatory by setting 'required=True', but
still allow the program to run with the option '--version' (which just
shows the version and then exits) even if the mandatory options are
missing.

Is there a standard way of doing this?

I see that instead of setting required to 'True' I can use an expression
which checks whether '--version' has been given:

parser.add_argument(
"uid", nargs="+",
help="UIDs to send mail to"
)
parser.add_argument(
'-s', '--subject', dest='subject', required=not '--version' in sys.argv,
help="subject of email"
)
parser.add_argument(
'-c', '--content_file', dest='content_file', required=not '--version' in sys.argv,
help="file containing mail contents (without salutation or signature)"
)
parser.add_argument(
'--version', action='store_true', dest='version',
help="print version"

However, with the above, I still need to specify the mandatory argument,
even if I only want to see the version.

I guess I'll just have to change

nargs="+"

to

nargs="*"

and check explicitly whether any arguments have been given.

Seems odd to me though that there is not a standard way of implementing '--version' which works like '--help' does.

Cheers,

Loris
--
This signature is currently under constuction.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.lang.python

On Thu, 30 Oct 2025 11:12:28 +0100, Loris Bennett wrote:

I am writing a program for the command-line which uses 'argsparse'. I
want to make some options mandatory by setting 'required=True', but
still allow the program to run with the option '--version' (which just
shows the version and then exits) even if the mandatory options are
missing.

Is there a standard way of doing this?

Crusty curmudgeon here, still sticking to good old getopt. It may be
simple, crude even, but on the other hand it doesn’t try to do too
much. It may be “soft-deprecated”, but at least that means it will
keep on doing what it does for the foreseeable future.

It doesn’t offer built-in help, but then I also like to write man
pages (yes, proper documentation) for my more complex scripts.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: comp.lang.python

Loris Bennett wrote:

"Loris Bennett" <[email protected]> writes:

Hi,

I am writing a program for the command-line which uses 'argsparse'. I
want to make some options mandatory by setting 'required=True', but
still allow the program to run with the option '--version' (which just
shows the version and then exits) even if the mandatory options are
missing.

Is there a standard way of doing this?

I see that instead of setting required to 'True' I can use an expression which checks whether '--version' has been given:

What I do is separate it into two functions. First function that sets up
the parser object and returns the parser object:

def make_parser() -> argparse.ArgumentParser:
parser = argparse.ArgumentParser( ... )
...
return parser

The code is similar to yours below, but for version my action references
an f string variable:

parser.add_argument(
"-v", "--version", action="version",
version=f"{APP_NAME} v{__version__}"
)


I typically have the optional args set to a default value, null string
or None. Then the second function which my main() calls this function
which returns a tuple of arg values here is one example:

def get_program_args() -> tuple:
parser = make_parser()
args = parser.parse_args()
return args.action, args.profile, args.log_level

def main():
# parser args
action, profile_name, log_level = get_program_args()
...

Works for me.

parser.add_argument(
"uid", nargs="+",
help="UIDs to send mail to"
)
parser.add_argument(
'-s', '--subject', dest='subject', required=not '--version' in sys.argv,
help="subject of email"
)
parser.add_argument(
'-c', '--content_file', dest='content_file', required=not '--version' in sys.argv,
help="file containing mail contents (without salutation or signature)"
)
parser.add_argument(
'--version', action='store_true', dest='version',
help="print version"

However, with the above, I still need to specify the mandatory argument,
even if I only want to see the version.

I guess I'll just have to change

nargs="+"

to

nargs="*"

and check explicitly whether any arguments have been given.

Seems odd to me though that there is not a standard way of implementing '--version' which works like '--help' does.

Cheers,

Loris

--
Take care,

Jonathan
-------------------
LITTLE WORKS STUDIO
http://www.LittleWorksStudio.com
--- Synchronet 3.21a-Linux NewsLink 1.2