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argparse: delimiter for argparse list arguments
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Sven R. Kunze
Aug 2, 2021, 3:52:33 PM8/2/21
to
Hi everyone,
maybe, I am missing something here but is it possible to specify a
delimiter for list arguments in argparse:
https://docs.python.org/3/library/argparse.html
Usually, '--' is used to separate two lists (cf. git).
Cheers,
Sven
maybe, I am missing something here but is it possible to specify a
delimiter for list arguments in argparse:
https://docs.python.org/3/library/argparse.html
Usually, '--' is used to separate two lists (cf. git).
Cheers,
Sven
Dan Stromberg
Aug 2, 2021, 7:50:26 PM8/2/21
to
Isn't -- usually used to signal the end of options?
> --
> https://mail.python.org/mailman/listinfo/python-list
>
> https://mail.python.org/mailman/listinfo/python-list
>
Michael Torrie
Aug 3, 2021, 10:46:01 AM8/3/21
to
On 8/2/21 1:43 PM, Sven R. Kunze wrote:
> Hi everyone,
>
> maybe, I am missing something here but is it possible to specify a
> delimiter for list arguments in argparse:
>
> https://docs.python.org/3/library/argparse.html
>
> Usually, '--' is used to separate two lists (cf. git).
I've not seen this syntax in git. Are you referring the the double and
> Hi everyone,
>
> maybe, I am missing something here but is it possible to specify a
> delimiter for list arguments in argparse:
>
> https://docs.python.org/3/library/argparse.html
>
> Usually, '--' is used to separate two lists (cf. git).
triple dot notation git uses? Can you give me an example of how git
uses -- as a list separator?
Typically -- on a command line means that's the end of the any special
switches and anything else, even if it looks like a command-line switch,
should not be parsed, and passed straight through as a normal parameter.
Jon Ribbens
Aug 3, 2021, 11:49:10 AM8/3/21
to
On 2021-08-03, Michael Torrie <tor...@gmail.com> wrote:
> On 8/2/21 1:43 PM, Sven R. Kunze wrote:
>> maybe, I am missing something here but is it possible to specify a
>> delimiter for list arguments in argparse:
>>
>> https://docs.python.org/3/library/argparse.html
>>
>> Usually, '--' is used to separate two lists (cf. git).
>
> I've not seen this syntax in git. Are you referring the the double and
> triple dot notation git uses? Can you give me an example of how git
> uses -- as a list separator?
Loads of git commands do this. e.g. commit, diff, log, status, etc.
> On 8/2/21 1:43 PM, Sven R. Kunze wrote:
>> maybe, I am missing something here but is it possible to specify a
>> delimiter for list arguments in argparse:
>>
>> https://docs.python.org/3/library/argparse.html
>>
>> Usually, '--' is used to separate two lists (cf. git).
>
> I've not seen this syntax in git. Are you referring the the double and
> triple dot notation git uses? Can you give me an example of how git
> uses -- as a list separator?
It's not completely unlike what you're describing above, which is
already supported automatically by argparse.
Roel Schroeven
Aug 3, 2021, 3:11:03 PM8/3/21
to
Jon Ribbens via Python-list schreef op 3/08/2021 om 17:48:
Commands like git commit do not use '--' to separate two lists, but as
Dan and Sven said to separate options from arguments, even if the
arguments start with '-' (like many other programs -- I think this is
standard in GNU). If you're 100% certain that none of the filenames
start with '-', you can leave out '--' without any change in behavior.
Especially when scripting and/or using wildcards it's best always to use
that '--' to avoid nasty surprises.
$ git commit -m "hello" -- hello.py
is exactly the same as
$ git commit -m "hello" hello.py
It's just that the former is safer to use, because it properly works
even in cases like
$ git commit -m "hello" -- -hello.py
whereas
$ git commit -m "hello" -hello.py
will likely not do what you expect.
As https://git-scm.com/docs/git-commit says:
> --
> Do not interpret any more arguments as options.
--
"The saddest aspect of life right now is that science gathers knowledge
faster than society gathers wisdom."
-- Isaac Asimov
Dan and Sven said to separate options from arguments, even if the
arguments start with '-' (like many other programs -- I think this is
standard in GNU). If you're 100% certain that none of the filenames
start with '-', you can leave out '--' without any change in behavior.
Especially when scripting and/or using wildcards it's best always to use
that '--' to avoid nasty surprises.
$ git commit -m "hello" -- hello.py
is exactly the same as
$ git commit -m "hello" hello.py
It's just that the former is safer to use, because it properly works
even in cases like
$ git commit -m "hello" -- -hello.py
whereas
$ git commit -m "hello" -hello.py
will likely not do what you expect.
As https://git-scm.com/docs/git-commit says:
> --
> Do not interpret any more arguments as options.
--
"The saddest aspect of life right now is that science gathers knowledge
faster than society gathers wisdom."
-- Isaac Asimov
Jon Ribbens
Aug 3, 2021, 4:56:05 PM8/3/21
to
On 2021-08-03, Roel Schroeven <ro...@roelschroeven.net> wrote:
> Jon Ribbens via Python-list schreef op 3/08/2021 om 17:48:
>> On 2021-08-03, Michael Torrie <tor...@gmail.com> wrote:
>> > On 8/2/21 1:43 PM, Sven R. Kunze wrote:
>> >> maybe, I am missing something here but is it possible to specify a
>> >> delimiter for list arguments in argparse:
>> >>
>> >> https://docs.python.org/3/library/argparse.html
>> >>
>> >> Usually, '--' is used to separate two lists (cf. git).
>> >
>> > I've not seen this syntax in git. Are you referring the the double and
>> > triple dot notation git uses? Can you give me an example of how git
>> > uses -- as a list separator?
>>
>> Loads of git commands do this. e.g. commit, diff, log, status, etc.
>> It's not completely unlike what you're describing above, which is
>> already supported automatically by argparse.
>
> Commands like git commit do not use '--' to separate two lists, but as
> Dan and Sven said to separate options from arguments,
That is not quite correct. Check out 'git diff' for example - it takes
> Jon Ribbens via Python-list schreef op 3/08/2021 om 17:48:
>> On 2021-08-03, Michael Torrie <tor...@gmail.com> wrote:
>> > On 8/2/21 1:43 PM, Sven R. Kunze wrote:
>> >> maybe, I am missing something here but is it possible to specify a
>> >> delimiter for list arguments in argparse:
>> >>
>> >> https://docs.python.org/3/library/argparse.html
>> >>
>> >> Usually, '--' is used to separate two lists (cf. git).
>> >
>> > I've not seen this syntax in git. Are you referring the the double and
>> > triple dot notation git uses? Can you give me an example of how git
>> > uses -- as a list separator?
>>
>> Loads of git commands do this. e.g. commit, diff, log, status, etc.
>> It's not completely unlike what you're describing above, which is
>> already supported automatically by argparse.
>
> Commands like git commit do not use '--' to separate two lists, but as
> Dan and Sven said to separate options from arguments,
as position arguments zero, one, or two commit hashes followed by zero
or more pathnames. You can use '--' to separate these two lists,
because of course sometimes a pathname can be indistinguishable from
a commit hash.
Sven R. Kunze
Aug 3, 2021, 5:06:40 PM8/3/21
to
It could be but I've seen them used somewhere else.
I wouldn't bikeshed on this yet, as I haven't found a way to do this so
far. Let's imagine the following parser:
parser.add_argument('things',action='append')
parser.add_argument('stuff',action='append')
At least from my point of view, I don't any way to separate both lists
on this command call:
cool-script.py thing1 thing2 stuff1 stuff2
Do I miss something here?
Best
Sven
On 03.08.21 01:49, Dan Stromberg wrote:
>
> Isn't -- usually used to signal the end of options?
>
> On Mon, Aug 2, 2021 at 12:52 PM Sven R. Kunze <srk...@mail.de
> <mailto:srk...@mail.de>> wrote:
>
> Hi everyone,
>
I wouldn't bikeshed on this yet, as I haven't found a way to do this so
far. Let's imagine the following parser:
parser.add_argument('things',action='append')
parser.add_argument('stuff',action='append')
At least from my point of view, I don't any way to separate both lists
on this command call:
cool-script.py thing1 thing2 stuff1 stuff2
Do I miss something here?
Best
Sven
On 03.08.21 01:49, Dan Stromberg wrote:
>
> Isn't -- usually used to signal the end of options?
>
> On Mon, Aug 2, 2021 at 12:52 PM Sven R. Kunze <srk...@mail.de
>
> Hi everyone,
>
> maybe, I am missing something here but is it possible to specify a
> delimiter for list arguments in argparse:
>
> https://docs.python.org/3/library/argparse.html
> <https://docs.python.org/3/library/argparse.html>
>
> Usually, '--' is used to separate two lists (cf. git).
>
> <https://mail.python.org/mailman/listinfo/python-list>
> maybe, I am missing something here but is it possible to specify a
> delimiter for list arguments in argparse:
>
> https://docs.python.org/3/library/argparse.html
> <https://docs.python.org/3/library/argparse.html>
>
> Usually, '--' is used to separate two lists (cf. git).
>
>
Chris Angelico
Aug 3, 2021, 5:21:24 PM8/3/21
to
On Wed, Aug 4, 2021 at 7:07 AM Sven R. Kunze <srk...@mail.de> wrote:
>
> It could be but I've seen them used somewhere else.
>
> I wouldn't bikeshed on this yet, as I haven't found a way to do this so
> far. Let's imagine the following parser:
>
> parser.add_argument('things',action='append')
> parser.add_argument('stuff',action='append')
>
> At least from my point of view, I don't any way to separate both lists
> on this command call:
>
>
> cool-script.py thing1 thing2 stuff1 stuff2
>
>
> Do I miss something here?
>
I'd probably design it like this:
>
> It could be but I've seen them used somewhere else.
>
> I wouldn't bikeshed on this yet, as I haven't found a way to do this so
> far. Let's imagine the following parser:
>
> parser.add_argument('things',action='append')
> parser.add_argument('stuff',action='append')
>
> At least from my point of view, I don't any way to separate both lists
> on this command call:
>
>
> cool-script.py thing1 thing2 stuff1 stuff2
>
>
> Do I miss something here?
>
cool-script.py --things thing1 thing2 --stuff stuff1 stuff2
which argparse already handles.
ChrisA
Roel Schroeven
Aug 3, 2021, 7:17:15 PM8/3/21
to
Jon Ribbens via Python-list schreef op 3/08/2021 om 22:55:
(commits and paths).
--
"Too often we hold fast to the cliches of our forebears. We subject all
facts to a prefabricated set of interpretations. Too often we enjoy the
comfort of opinion without the discomfort of thought."
-- John F Kennedy
> >> Loads of git commands do this. e.g. commit, diff, log, status, etc.
> >> It's not completely unlike what you're describing above, which is
> >> already supported automatically by argparse.
> >
> > Commands like git commit do not use '--' to separate two lists, but as
> > Dan and Sven said to separate options from arguments,
>
> That is not quite correct. Check out 'git diff' for example - it takes
> as position arguments zero, one, or two commit hashes followed by zero
> or more pathnames. You can use '--' to separate these two lists,
> because of course sometimes a pathname can be indistinguishable from
> a commit hash.
Ah yes, I stand corrected, git diff indeed uses -- to separate two lists
> >> It's not completely unlike what you're describing above, which is
> >> already supported automatically by argparse.
> >
> > Commands like git commit do not use '--' to separate two lists, but as
> > Dan and Sven said to separate options from arguments,
>
> That is not quite correct. Check out 'git diff' for example - it takes
> as position arguments zero, one, or two commit hashes followed by zero
> or more pathnames. You can use '--' to separate these two lists,
> because of course sometimes a pathname can be indistinguishable from
> a commit hash.
(commits and paths).
--
"Too often we hold fast to the cliches of our forebears. We subject all
facts to a prefabricated set of interpretations. Too often we enjoy the
comfort of opinion without the discomfort of thought."
-- John F Kennedy
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