No hint for missing argument

> When you type an option that requires an argument, but don't provide one, you get an error message that says there is a missing argument. There should brobably be a hint on what values are acceptable. For instance, there is no way to know from "guix package -v" or "guix package --help" what values are accepted. In other cases, there is a --list-something option.

>

> Maybe -v is the only case where it would be useful to do something, because you could guess its existence and not use a verbosity level. Maybe fixing the help message to say --verbosity=[0-5] is enough?

> Julien Lepiller <julien@lepiller.eu> skribis:

>

> > When you type an option that requires an argument, but don't

> > provide one, you get an error message that says there is a missing

> > argument. There should brobably be a hint on what values are

> > acceptable. For instance, there is no way to know from "guix

> > package -v" or "guix package --help" what values are accepted. In

> > other cases, there is a --list-something option.

> >

> > Maybe -v is the only case where it would be useful to do something,

> > because you could guess its existence and not use a verbosity

> > level. Maybe fixing the help message to say --verbosity=[0-5] is

> > enough?

>

> Currently it says:

>

> --8<---------------cut here---------------start------------->8---

> $ guix build --help | grep -e -verbo

> -v, --verbosity=LEVEL use the given verbosity LEVEL

> --8<---------------cut here---------------end--------------->8---

>

> We could add “an integer between 0 and 2”, but this was left

> non-explicit in case we eventually extend it to -7 to +42.

>

> Maybe there’s a limit on what we can do to help users? :-)

>

> Ludo’.

> Le Thu, 11 Jul 2019 22:40:58 +0200,

> Ludovic Courtès <ludo@gnu.org> a écrit :

>> Currently it says:

>>

>> --8<---------------cut here---------------start------------->8---

>> $ guix build --help | grep -e -verbo

>> -v, --verbosity=LEVEL use the given verbosity LEVEL

>> --8<---------------cut here---------------end--------------->8---

>>

>> We could add “an integer between 0 and 2”, but this was left

>> non-explicit in case we eventually extend it to -7 to +42.

>>

>> Maybe there’s a limit on what we can do to help users? :-)

>>

>> Ludo’.

>

> If users have no idea what value to use though, they just won't use the

> feature...