[KPhotoAlbum] KIM File format compatibility

[Robert Krawitz]

On Thu, 18 May 2017 22:30:49 +0200, Johannes Zarl-Zierl wrote:
> On Donnerstag, 18. Mai 2017 00:10:39 CEST Joe wrote:
>> >> A proper fix needs to change the way we create export files. In the
>> >> past, I was always hesitant to touch the .kim file format in order
>> >> to avoid compatibility problems. Maybe it's time to revisit this
>> >> decision...
>> > 
>> > I agree it needs to be backward compatible, so a newer kpa can import
>> > an older .kim file.  I don't think the other direction is necessary;
>> > if an old kpa can't import a new import file, you upgrade.
>> 
>> While I totally agree with this in principle, sometimes you can't
>> upgrade because of dependencies.
>> I had an install of something from a tarball fail today because of that.
>> 
>> The question then becomes: Are there any plausible scenarios where you
>> would have a newer version the .kim file (which had to be generated on a
>> newer version of KPA to start with) and still need to use it with an
>> older version of KPA. I don't know the answer. E.g., Do all users have
>> QT5 installed?
>
> Qt5 is probably not the issue here. I see more of a point in users
> sticking to the stable version of some distro for one machine, but
> using another more bleeding-edge type of distro on another machine.

Then they're going to have a lot of other problems moving things back
and forth, not just kpa (think about their other desktop settings).
And if they stick to populating the database originally on the stable
machine, and then importing the changes to the unstable machine, they
can avoid it.

> For changing the file format, I would propose action along the following line:
> - Change the file extension (what about .kpx?)

Yeah, .kim sounds like it refers to the old name for the project.

> - Add versioning to the file format, like we do have with the index.xml

Likewise.

> - Disable new, incompatible options in the export dialog when a legacy .kim file is requested

If you restrict it to just the legacy .kim file, OK.  If you allow
choice of format to export to, it will become messy way too fast.
-- 
Robert Krawitz                                     <rlk at alum.mit.edu>

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