Default Program | File Association

[Mhall]

All of these seems to be steering closer and closer to theDebian alternatives database, could we just use that with a mime type instead of a task name?  It already has support for applications to add/remove themselves with a priority number, allows the user to easily change priority and/or set which one to use.

http://www.debian-administration.org/articles/91

-----Original message-----
From: David Faure dfaure at trolltech.com
Date: Tue, 29 Jan 2008 11:17:17 -0500
To: Stanislav Brabec sbrabec at suse.cz
Subject: Re: Default Program | File Association

> On Tuesday 29 January 2008, Stanislav Brabec wrote:
> > 
> > It is a very complex task to create correct defaults.list using the
> > current format. For example (GNOME), you have to do manually:
> > 
> > - Fill eog.desktop for all image MIME types mentioned in eog.desktop
> > 
> > - Find all MIME types not mentioned in eog.desktop but opened by another
> >   GTK/GNOME viewer and fill this viewer to these MIME types.
> > 
> > - Find all MIME types not opened by any of above and fill generic image
> >   viewer there.
> > 
> > It is even a fragile task - if any of the image viewers is removed,
> > there is no way to find "second best fit" and application has to choose
> > randomly.
> 
> The above is exactly why applications should *NOT* touch defaults.list files IMHO.
> Those files exist to save the user's preference, possibly a sysadmin preference, but only that.
> 
> Applications should simply install a .desktop file that describes them.
> In order for the default order of applications (i.e. without user configuration available)
> to be non-random, we (in KDE) use a InitialPreference field in the .desktop file,
> and the default application for a mimetype is the one with the highest initial preference number.
> 
> You might say: but then every application will use 4 billion or more in that field,
> but I have actually never seen that happen (and this would be equivalent with app installers
> modifying defaults.list anyway, so no difference there).
> In practice people use reasonable numbers (between 1 and 10) and this feature 
> allows KDE releases to come out with a predefined application order, which allows to 
> make sure that the order isn't stupid: for instance, even though karbon can sort 
> of import postscript files (so karbon.desktop mentions application/postscript), kghostview 
> was a much better default application for viewing postscript; so we simply made 
> sure that kghostview had a higher InitialPreference than karbon.
> This example also shows that InitialPreference really has to be per-mimetype supported
> in a given desktop file, not just for the whole desktop file (although that's good enough
> in 95% of the cases of course). Hence my suggestion in a previous mail, for a new 
> section in .desktop files which defines per-mimetype initial preference:
> [InitialPreferences]
> text/plain=2
> application/postscript=6
> 
> (this makes this application preferred over another app that has <6 for application/postscript,
> but if a third application handles text better then it will be used instead of this one).
> 
> I would really like this clean solution (cleaner than kde's current hack for
> per-mimetype preference numbers) to be added to the desktop entry standard.
> 
> -- 
> David Faure, faure at kde.org, sponsored by Trolltech to work on KDE,
> Konqueror (http://www.konqueror.org), and KOffice (http://www.koffice.org).
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