[Freeciv-Dev] backward compatability of saved games

[Jason Dorje Short <jdorje@xxxxxxxxxxxx>]

In the past we have discussed how gen-eff may necessitate the breaking 
of savegame backward compatibility.  I don't think this is true, but it 
does bring up the idea...
There is a _lot_ of stuff in savegame.c to preserve backward 
compatibility.  Nobody really knows how far back compatibility goes. 
When writing new code we preserve compatibility with the previous 
savegame format but we could easily break compatibility with even older 
savegame formats and not even know it (for this reason I'm afraid to 
change anything in savegame.c).
There is something to be said for a one-time breaking of compatibility. 
 It would allow the removal of hundreds of lines of code in savegame.c 
and the logic could be cleaned up so that we actually understand it.  We 
could then mark a definite point that savegames must be compatible with, 
and make some publically available savegames that can be used for 
testing of future code.
However the new compatibility period wouldn't kick in until the next 
release; until then we would be free to break compatibility some more. 
In the meantime we should fix many of the ruleset incompatibilities 
(changing the ruleset breaks savegame compatibility unless you're really 
careful, in part because the savegame depends unnecessarily on the order 
of elements in the ruleset).
I'm not sure if I'm in favor of this idea.  It is really a way to 
simplify the code at the expense of the user.  However because the code 
is simpler it will be end up with faster, less buggy development, so the 
user will benefit as well.
What do other people think?

jason