Adam Lally wrote:
On 5/29/07, Thilo Goetz <[EMAIL PROTECTED]> wrote:
KANO, Yoshinobu wrote:
> Hello,
>
> The UIMA type system should be compliant to ecore/EMF, as far as I
know,
> and there are a mapping definition between ecore and Java.
>
> But the current Apache UIMA implementation does not allow any multiple
> inheritances.
> If we define a second supertype in the definition file,
> UIMA Eclipse plugin will delete it automatically.
> The ECore2UIMATypeSystem converter also does not support real multiple
> inheritances.
>
> Are there any plan to support multiple inheritances?
> If any, when will it be - roughly speaking, two or three months, or
half
> a year?
>
> best regards,
>
> Yoshinobu
We don't currently have any plans to add multiple inheritance to the type
system (or at least I don't). It's not that difficult in principle, as
multiple inheritence at the data level is relatively unproblematic.
There
are a few assumptions about each type having a unique parent strewn
through
the code, but nothing major I think. If anybody wants to work on this,
feel free to make a proposal.
Also JCAS would need to be considered. Since JCAS cover classes are
currently classes, not interfaces, there's no way a JCAS cover class
could have two supertypes. So I think supporting multiple inheritance
would also involve a new JCAS design using interfaces.
-Adam
Yes, I hadn't thought of that. I guess it wouldn't be too hard to do, but
it would mean a non-backward compatible change I think. And I don't think
we're ready for that, at least not in the 2.x branch.
--Thilo
