bug#13824: 24.3.50; :package-version not taking priority over :version

bug#13824: 24.3.50; :package-version not taking priority over :version

[Bastien Guerry]

The docstring of `defcustom' says:

:package-version
        VALUE should be a list with the form (PACKAGE . VERSION)
        specifying that the variable was first introduced, or its
        default value was changed, in PACKAGE version VERSION.  This
        keyword takes priority over :version.
        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

but `describe-variable-custom-version-info' gives priority to :version
over :package-version.  Which one is correct here?

Thanks!

bug#13824: 24.3.50; :package-version not taking priority over :version

[Stefan Kangas]

Bastien Guerry <bzg@altern.org> writes:

> The docstring of `defcustom' says:
>
> :package-version
>         VALUE should be a list with the form (PACKAGE . VERSION)
>         specifying that the variable was first introduced, or its
>         default value was changed, in PACKAGE version VERSION.  This
>         keyword takes priority over :version.
>         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> but `describe-variable-custom-version-info' gives priority to :version
> over :package-version.  Which one is correct here?

This is still an issue on current master (and 26.2).

I reproduced this using:

    (progn
      (defcustom foobar nil
        "foo"
        :version "27.1"
        :package-version '(foo . "1"))
      (describe-variable-custom-version-info 'foobar))

Which results in:

    "This variable was introduced, or its default value was changed, in
    version 27.1 of Emacs.
    "

But C-h f defcustom says:

    :package-version
            VALUE should be a list with the form (PACKAGE . VERSION)
            specifying that the variable was first introduced, or its
            default value was changed, in PACKAGE version VERSION.  This
            keyword takes priority over :version.

Thanks,
Stefan Kangas

bug#13824: 24.3.50; :package-version not taking priority over :version

[Eli Zaretskii]

> From: Stefan Kangas <stefan@marxist.se>
> Date: Thu, 8 Aug 2019 05:59:21 +0200
> Cc: 13824@debbugs.gnu.org
> 
> Bastien Guerry <bzg@altern.org> writes:
> 
> > The docstring of `defcustom' says:
> >
> > :package-version
> >         VALUE should be a list with the form (PACKAGE . VERSION)
> >         specifying that the variable was first introduced, or its
> >         default value was changed, in PACKAGE version VERSION.  This
> >         keyword takes priority over :version.
> >         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> >
> > but `describe-variable-custom-version-info' gives priority to :version
> > over :package-version.  Which one is correct here?
> 
> This is still an issue on current master (and 26.2).
> 
> I reproduced this using:
> 
>     (progn
>       (defcustom foobar nil
>         "foo"
>         :version "27.1"
>         :package-version '(foo . "1"))
>       (describe-variable-custom-version-info 'foobar))
> 
> Which results in:
> 
>     "This variable was introduced, or its default value was changed, in
>     version 27.1 of Emacs.
>     "
> 
> But C-h f defcustom says:
> 
>     :package-version
>             VALUE should be a list with the form (PACKAGE . VERSION)
>             specifying that the variable was first introduced, or its
>             default value was changed, in PACKAGE version VERSION.  This
>             keyword takes priority over :version.

The implementation only prefers :package-version for the purposes of
customize-changed-options, i.e. the Options->Customize Emacs->New
Options menu item.  By contrast, describe-variable-custom-version-info
is used for displaying the doc strings of options.  For a package that
is bundled with Emacs, I think displaying :version in "C-h v" makes
sense.  If people agree, then this is a minor documentation bug (also
to be fixed in the ELisp manual), not a code bug.

Bill, what is your take on this?  Your change, which introduced this
attribute, only modified customize-changed-options.  Was that on
purpose?

bug#13824: 24.3.50; :package-version not taking priority over :version

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

> For a package that
> is bundled with Emacs, I think displaying :version in "C-h v" makes
> sense.  If people agree, then this is a minor documentation bug (also
> to be fixed in the ELisp manual), not a code bug.

Yes, that makes sense.  Let's see what Bill says.

Thanks,
Stefan Kangas

bug#13824: 24.3.50; :package-version not taking priority over :version

[Bill Wohler]

Eli Zaretskii <eliz@gnu.org> wrote:

> > From: Stefan Kangas <stefan@marxist.se>
> > Date: Thu, 8 Aug 2019 05:59:21 +0200
> > Cc: 13824@debbugs.gnu.org
> > 
> > Bastien Guerry <bzg@altern.org> writes:
> > 
> > > The docstring of `defcustom' says:
> > >
> > > :package-version
> > >         VALUE should be a list with the form (PACKAGE . VERSION)
> > >         specifying that the variable was first introduced, or its
> > >         default value was changed, in PACKAGE version VERSION.  This
> > >         keyword takes priority over :version.
> > >         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > >
> > > but `describe-variable-custom-version-info' gives priority to :version
> > > over :package-version.  Which one is correct here?
> > 
> > This is still an issue on current master (and 26.2).
> > 
> > I reproduced this using:
> > 
> >     (progn
> >       (defcustom foobar nil
> >         "foo"
> >         :version "27.1"
> >         :package-version '(foo . "1"))
> >       (describe-variable-custom-version-info 'foobar))
> > 
> > Which results in:
> > 
> >     "This variable was introduced, or its default value was changed, in
> >     version 27.1 of Emacs.
> >     "
> > 
> > But C-h f defcustom says:
> > 
> >     :package-version
> >             VALUE should be a list with the form (PACKAGE . VERSION)
> >             specifying that the variable was first introduced, or its
> >             default value was changed, in PACKAGE version VERSION.  This
> >             keyword takes priority over :version.
> 
> The implementation only prefers :package-version for the purposes of
> customize-changed-options, i.e. the Options->Customize Emacs->New
> Options menu item.  By contrast, describe-variable-custom-version-info
> is used for displaying the doc strings of options.  For a package that
> is bundled with Emacs, I think displaying :version in "C-h v" makes
> sense.  If people agree, then this is a minor documentation bug (also
> to be fixed in the ELisp manual), not a code bug.
> 
> Bill, what is your take on this?  Your change, which introduced this
> attribute, only modified customize-changed-options.  Was that on
> purpose?

Thanks for asking. The original intent of package-version was to provide
more accurate version information in packages that were updated more
often than Emacs, regardless of whether they were packaged in Emacs
(like MH-E and Gnus) or not. I think that should apply to any function
that displays version information for an option. That is, any function
that looks for :version should also look for :package-version.

-- 
Bill Wohler <wohler@newt.com> aka <Bill.Wohler@nasa.gov>
http://www.newt.com/wohler/, GnuPG ID:610BD9AD

bug#13824: 24.3.50; :package-version not taking priority over :version

[Bill Wohler]

Bill Wohler <wohler@newt.com> wrote:

> Eli Zaretskii <eliz@gnu.org> wrote:
> 
> > > From: Stefan Kangas <stefan@marxist.se>
> > > Date: Thu, 8 Aug 2019 05:59:21 +0200
> > > Cc: 13824@debbugs.gnu.org
> > > 
> > > Bastien Guerry <bzg@altern.org> writes:
> > > 
> > > > The docstring of `defcustom' says:
> > > >
> > > > :package-version
> > > >         VALUE should be a list with the form (PACKAGE . VERSION)
> > > >         specifying that the variable was first introduced, or its
> > > >         default value was changed, in PACKAGE version VERSION.  This
> > > >         keyword takes priority over :version.
> > > >         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> > > >
> > > > but `describe-variable-custom-version-info' gives priority to :version
> > > > over :package-version.  Which one is correct here?
> > > 
> > > This is still an issue on current master (and 26.2).
> > > 
> > > I reproduced this using:
> > > 
> > >     (progn
> > >       (defcustom foobar nil
> > >         "foo"
> > >         :version "27.1"
> > >         :package-version '(foo . "1"))
> > >       (describe-variable-custom-version-info 'foobar))
> > > 
> > > Which results in:
> > > 
> > >     "This variable was introduced, or its default value was changed, in
> > >     version 27.1 of Emacs.
> > >     "
> > > 
> > > But C-h f defcustom says:
> > > 
> > >     :package-version
> > >             VALUE should be a list with the form (PACKAGE . VERSION)
> > >             specifying that the variable was first introduced, or its
> > >             default value was changed, in PACKAGE version VERSION.  This
> > >             keyword takes priority over :version.
> > 
> > The implementation only prefers :package-version for the purposes of
> > customize-changed-options, i.e. the Options->Customize Emacs->New
> > Options menu item.  By contrast, describe-variable-custom-version-info
> > is used for displaying the doc strings of options.  For a package that
> > is bundled with Emacs, I think displaying :version in "C-h v" makes
> > sense.  If people agree, then this is a minor documentation bug (also
> > to be fixed in the ELisp manual), not a code bug.
> > 
> > Bill, what is your take on this?  Your change, which introduced this
> > attribute, only modified customize-changed-options.  Was that on
> > purpose?
> 
> Thanks for asking. The original intent of package-version was to provide
> more accurate version information in packages that were updated more
> often than Emacs, regardless of whether they were packaged in Emacs
> (like MH-E and Gnus) or not. I think that should apply to any function
> that displays version information for an option. That is, any function
> that looks for :version should also look for :package-version.

And to answer your question directly, if I didn't change other
functions, it was not on purpose.

By the way, I just checked and describe-variable-custom-version-info,
which was added in 2007, did not yet exist when I added :package-version
in 2006.

-- 
Bill Wohler <wohler@newt.com> aka <Bill.Wohler@nasa.gov>
http://www.newt.com/wohler/, GnuPG ID:610BD9AD

bug#13824: 24.3.50; :package-version not taking priority over :version

[Eli Zaretskii]

> cc: Stefan Kangas <stefan@marxist.se>, bzg@altern.org,
>     13824@debbugs.gnu.org
> From: Bill Wohler <wohler@newt.com>
> Date: Sat, 10 Aug 2019 15:10:13 -0700
> 
> > Bill, what is your take on this?  Your change, which introduced this
> > attribute, only modified customize-changed-options.  Was that on
> > purpose?
> 
> Thanks for asking. The original intent of package-version was to provide
> more accurate version information in packages that were updated more
> often than Emacs, regardless of whether they were packaged in Emacs
> (like MH-E and Gnus) or not. I think that should apply to any function
> that displays version information for an option. That is, any function
> that looks for :version should also look for :package-version.

Thanks.

Upon taking a better look, I conclude that there's more here than
originally met the eye.

First, the doc string of defcustom says:

  :package-version
	  VALUE should be a list with the form (PACKAGE . VERSION)
	  specifying that the variable was first introduced, or its
	  default value was changed, in PACKAGE version VERSION.  This
	  keyword takes priority over :version.  For packages which
	  are bundled with Emacs releases, the PACKAGE and VERSION
	  must appear in the alist `customize-package-emacs-version-alist'.
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

So Stefan's reproducer, viz.:

    (progn
      (defcustom foobar nil
        "foo"
        :version "27.1"
        :package-version '(foo . "1"))
      (describe-variable-custom-version-info 'foobar))

wasn't supposed to work, since it doesn't play by the rules.

Next, MH-E uses :package-version, but doesn't use :version.  So, for
example, "C-h v mh-whitelist-preserves-sequences-flag RET" produces
the expected

  This variable was introduced, or its default value was changed, in
  version 8.4 of the MH-E package that is part of Emacs 24.4.

By contrast, Org mode files use both :package-version and :version,
which I guess was the reason why Bastien filed this bug report in the
first place.

Now, since we _require_ the package versions to appear in
customize-package-emacs-version-alist, specifying :package-version
alone provides all the info we need about both the package version and
the corresponding Emacs version.  Therefore, specifying :version as
well is simply redundant when :package-version is given, and Org
shouldn't use :version (btw, Org is the only bundled package which
uses both these attributes).  IOW, if a package uses both attributes,
it's a mistake, we should document that to be a mistake (i.e. not just
say :package-version "overrides"), and it should probably be flagged
as a mistake by checkdoc.  And yes, functions that need the version
information should ignore :version if :package-version is available.
Which means describe-variable-custom-version-info should indeed be
fixed.

Thanks.

bug#13824: 24.3.50; :package-version not taking priority over :version

[Bill Wohler]

Eli Zaretskii <eliz@gnu.org> wrote:

> > cc: Stefan Kangas <stefan@marxist.se>, bzg@altern.org,
> >     13824@debbugs.gnu.org
> > From: Bill Wohler <wohler@newt.com>
> > Date: Sat, 10 Aug 2019 15:10:13 -0700
> > 
> > > Bill, what is your take on this?  Your change, which introduced this
> > > attribute, only modified customize-changed-options.  Was that on
> > > purpose?
> > 
> > Thanks for asking. The original intent of package-version was to provide
> > more accurate version information in packages that were updated more
> > often than Emacs, regardless of whether they were packaged in Emacs
> > (like MH-E and Gnus) or not. I think that should apply to any function
> > that displays version information for an option. That is, any function
> > that looks for :version should also look for :package-version.
> 
> Thanks.
> 
> Upon taking a better look, I conclude that there's more here than
> originally met the eye.
> 
> First, the doc string of defcustom says:
> 
>   :package-version
> 	  VALUE should be a list with the form (PACKAGE . VERSION)
> 	  specifying that the variable was first introduced, or its
> 	  default value was changed, in PACKAGE version VERSION.  This
> 	  keyword takes priority over :version.  For packages which
> 	  are bundled with Emacs releases, the PACKAGE and VERSION
> 	  must appear in the alist `customize-package-emacs-version-alist'.
>           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> So Stefan's reproducer, viz.:
> 
>     (progn
>       (defcustom foobar nil
>         "foo"
>         :version "27.1"
>         :package-version '(foo . "1"))
>       (describe-variable-custom-version-info 'foobar))
> 
> wasn't supposed to work, since it doesn't play by the rules.
> 
> Next, MH-E uses :package-version, but doesn't use :version.  So, for
> example, "C-h v mh-whitelist-preserves-sequences-flag RET" produces
> the expected
> 
>   This variable was introduced, or its default value was changed, in
>   version 8.4 of the MH-E package that is part of Emacs 24.4.
> 
> By contrast, Org mode files use both :package-version and :version,
> which I guess was the reason why Bastien filed this bug report in the
> first place.
> 
> Now, since we _require_ the package versions to appear in
> customize-package-emacs-version-alist, specifying :package-version
> alone provides all the info we need about both the package version and
> the corresponding Emacs version.  Therefore, specifying :version as
> well is simply redundant when :package-version is given, and Org
> shouldn't use :version (btw, Org is the only bundled package which
> uses both these attributes).  IOW, if a package uses both attributes,
> it's a mistake, we should document that to be a mistake (i.e. not just
> say :package-version "overrides"), and it should probably be flagged
> as a mistake by checkdoc.  And yes, functions that need the version
> information should ignore :version if :package-version is available.
> Which means describe-variable-custom-version-info should indeed be
> fixed.

Thanks for digging in. That makes sense. A function that gets the
version info from :package-version or :version as appropriate could be
written (if it hasn't already). If used consistently throughout, it
would provide a good example for obtaining version information.

> 
> Thanks.
> 

-- 
Bill Wohler <wohler@newt.com> aka <Bill.Wohler@nasa.gov>
http://www.newt.com/wohler/, GnuPG ID:610BD9AD