Re: MIME database

[brendan . tildesley]

(Apparently I replied only to Andy but not the mailing list by accident, so I'm 
sending this again)
> On Tue 28 Nov 2017 12:23, Alex Vong <address@hidden> writes:
> 
>> julien lepiller <address@hidden> writes:
>>
>>> Le 2017-11-28 10:24, address@hidden a écrit :
>>>> address@hidden skribis:
>>>>
[...]
> 
> I think it's reasonable to want to be able to open PDFs in inkscape or
> GIMP (e.g. via the "Open With" menu in a file browser like Nautilus),
> just that they shouldn't be the default option.  I think removing the
> association would be a not-so-good option; the blessed way to fix this
> is apparently to install a set of defaults.
> 
> Specifically we should add to this package from gnome.scm to include the
> PDF -> evince association:
> 
>     (define-public gnome-default-applications
>       (package
>         (name "gnome-default-applications")
>         (version "0")
>         (build-system trivial-build-system)
>         (source #f)
>         (propagated-inputs
>          `(("nautilus" ,nautilus)))
>         (arguments
>          `(#:modules ((guix build utils))
>            #:builder
>            (begin
>              (use-modules (guix build utils))
>              (let* ((out (assoc-ref %outputs "out"))
>                     (apps (string-append out "/share/applications")))
>                (mkdir-p apps)
>                (call-with-output-file (string-append apps "/defaults.list")
>                  (lambda (port)
>                    (format port "[Default Applications]\n")
>                    (format port 
> "inode/directory=org.gnome.Nautilus.desktop\n")))
>                #t))))
>         (synopsis "Default MIME type associations for the GNOME desktop")
>         (description
>          "Given many installed packages which might handle a given MIME type, 
> a
>     user running the GNOME desktop probably has some preferences: for example,
>     that folders be opened by default by the Nautilus file manager, not the 
> Baobab
>     disk usage analyzer.  This package establishes that set of default MIME 
> type
>     associations for GNOME.")
>         (license license:gpl3+)
>         (home-page #f)))
> 
> Possibly we could have a set of defaults for XFCE as well.  See also
> https://wiki.archlinux.org/index.php/default_applications#XDG_standard.
> 
> Andy
That wiki points to 
https://standards.freedesktop.org/mime-apps-spec/mime-apps-spec-latest.html

I stumbled across this thread 
https://mail.gnome.org/archives/distributor-list/2015-January/msg00000.html
That claims defaults.list is deprecated.

Following the latest spec, gnome-default applications should create 
mimeapps.list instead of defaults.list, or perhaps gnome-mimeapps.list, which 
will then be used if XDG_CURRENT_DESKTOP=GNOME .
With {gnome,xcfe,...]-mimeapps.list, multiple non-conflicting mimeapps.list 
files can be installed and used appropriately when one logs in to a particular 
desktop environment.

Why does gnome-default-applications have nautilus as a propagated-input? I'd 
have expected such a package to merely install the mimedata and do nothing 
else. And currently it just installs one line for nautilus.
Fedora-Workstation has the file 
http://pkgs.fedoraproject.org/cgit/rpms/shared-mime-info.git/tree/gnome-mimeapps.list
 as a part of "shared-mime-data". When I launched Fedora in VM, I found it also 
has this identical file at 

/usr/share/applications/mimedata.list
as well ass
/usr/share/applications/gnome-mimedata.list

I'm not sure why they chose to do that.

I'm wondering what people like me who use tiling window managers should do. 
Should we install such a file and set XDG_CURRENT_DESKTOP=GNOME to get the 
benefit of GNOME defaults? But then mixing applications from multiple desktops 
becomes an issue.
The thing I want to achieve is good *defaults*, but installing such things and 
setting a variable directly contradicts that. This implies the solution 
probably ought to involve modifying shared-mime-info or xdg-mime-database such 
that the resulting mime data generated by update-mime-database embeds these 
common-sense defaults like preferring Evince/Okular over Gimp for PDF files. 
The mime-apps specs even labels the system installed mimeapps.list files as 
"distribution-provided defaults" suggesting that it is the role of distribution 
developers to manipulate these files as they see fit to produce good defaults. 
Although, how would one do it without making Okular appear in the list of 
applications even when it is not actually installed? I'll have to investigate 
how update-mime-database works.