[ http://issues.apache.org/jira/browse/OJB-65?page=comments#action_12318163 
] 

Luis Fernando Pollo commented on OJB-65:
----------------------------------------

We've had a discussion regarding this subject early last year, which is 
registered in the mail archive and might be worth reading:

http://mail-archives.apache.org/mod_mbox/db-ojb-dev/200404.mbox/[EMAIL 
PROTECTED]

It's not just about inheriting field descriptors in a derived class. It's about 
inheriting *everything* from fields, to references, to collections, as you 
would expect in any object oriented design. It's an *O*RM solution, after all, 
isn't it? It's important to balance focus between the 'O' and the 'R' parts, 
otherwise you start worrying about persistence when you're doing OO design -- 
and whether or not framework A or B will support what you're designing --, 
which is just bad.  From my point of view, you've got to be able to define your 
OR mappings in OJB in a way similar to how you define your classes in Java.

I think it's important that the current inheritance mapping mechanisms be 
seriously overhauled for 1.1, since there are essencial/desirable features that 
are either missing or not working propertly at the moment, most notably the 
incorrect handling of mappings on multiple joined tables (see issue OJB-63) and 
the inheritance of mappings from base classes (see above).

Have you guys taken a look at the way hibernate handles inheritance mapping, 
for example, and even considered doing something similar? I have a feeling you 
might be reinventing the wheel here. They have a pretty concise way of defining 
inheritance there, maybe it's worth taking a good look at.

> Allow field-descriptor inheritance for sub-classes
> --------------------------------------------------
>
>          Key: OJB-65
>          URL: http://issues.apache.org/jira/browse/OJB-65
>      Project: OJB
>         Type: Wish
>     Versions: 1.0.x CVS
>     Reporter: Armin Waibel

>
> When using "extent-classes" the field-descriptor declared in the 
> super-classes will not be inherited to the sub-classes. Each sub-class have 
> to declare all fields of the super-classes.
> Think the inheritance of fields declared in super-classes could be handled by 
> the metadata classes when reading the repository file. When we introduce an 
> attribute 'allowInherit' in class-descriptor and field-descriptor element (by 
> default it's 'true' in CLD and "undefined" in FLD), OJB will be able to 
> inherit copies (copies needed, because each field-descriptor is associated 
> with a class-descriptor) of field-descriptor instances to the sub-classes. 

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