Re: Improving lifeline objects behaviour

[Lars Clausen <lars raeder dk>]

On Sun, 2007-09-02 at 11:02 +0200, Filippo Bergamasco wrote:
> Lars,
> I'm glad to see that you have tested my patch and appreciated my idea!
> Maybe i didn't point out that that was a quick hack used mostly as an
> experiment to improve lifeline usability instead of a definitive
> change to the code. My first aim was to change its behaviour by
> modifying as less as possible to avoid side-effects or accidentally
> destroy compatibility with old versions. 
>
> So.. by your leave.. now i would like to _partially_ re-write lifeline
> code making this big but (imho) necessary changes:
>
> 1) Change overall behaviour as shown in my previous patch, but with
> the care to let cp_distance be a property of lifeline object (magic is
> bad.. sir, yes sir!  <-- i also agree to this) 
>
> 2) Solve the boring problem to have 2 cp_lines by side plus 6 fixed cp
> just to quickly mantain backward compatibility

Please!  It's awful!

> 3) Create a _very_ simple gui to let users adjust cp_distance by a
> specific value instead of hardcoded increments (<-- this one needs
> your ok ) 

I do believe this will come automatically as part of 1).  Make the
property a PROP_TYPE_LENGTH and you even get units.  Just remember to
set PROP_FLAG_OPTIONAL to allow loading of old objects without this
value.

> 4) Mantain compatibility with older versions by _converting_ old
> objects to new ones while loading. This is actually the main problem
> for me because i didn't figure out well how objects are saved/loaded..
> can you give me a quick advice about where to look for some
> informations?  Is also necessary to convert new objects to old ones
> while saving? 

Don't worry about converting to old style, forwards compatibility is not
as important in pre-1.0 as improvements.

Most of what there is of coding documentation outside the source is at
<URL:http://faemalia.org/wiki/view/Technical/DiaEditor>.  You can use
the version parameter to check whether you need to convert from old
style.

> Unfortunately now I'm so busy with exams so I'm asking you to give me
> some time to do and test all these, but it will ends up to a nice
> work.. i promise :)

Sounds good.  I know all about being busy:)  I'll apply the patch you
sent, since it doesn't break any compatibility anyway, and then you can
work off of SVN.

> ps. 
> What about document what I've found? What exactly I'll have to do?
> Just comment my code or...?

Comment the code, yes please.  JavaDoc style is preferred.

-Lars