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Date: Wed, 29 Jun 2011 11:41:42 -0700 (PDT)
From: Pinaki Poddar <ppoddar@apache.org>
To: dev@openjpa.apache.org
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Subject: Re: Metamodel generates ListAttribute for arrays instead of
 SingularAttribute
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Arrays are specialized Lists. Or Lists are specialized Arrays. Like Rectangle
is a specialized Square. Or Square is a specialized Rectangle. Formal
language inheritance concept does not pin this either way but allows one to
consider either view. 

OpenJPA had so far modeled Array as second-class container in a consistent
manner as it did for java.util.Collection and its subtypes. I support such
modeling. It also has an extra makeDirty() because of technical complexity
of tracking changes in second-class containers w.r.t Arrays. 

>From that viewpoint of maintaining continuity of design principles of the
original authors, the modeling of Array as List is correct, imo.  

Primitive collection requires different treatment. That is why JPA 2.0 had
to annotate @ElementCollection to distinguish from reference collection. Let
us keep that aside for the time being.

Now on why "X spec says so..." is a weak argument

Specs are combined voices of you and I and all the people who are brave and
crazy enough to explore new ideas in open source projects. Specs follow Open
Source. Not the other way around. Open Source is the playground where
technical debate (as we are now engaged in) takes place, where new ideas
emerge. If the ideas are solid and the democracy of users accept it -- then
the spec of future years will adopt it. 

As far as persistence of Arrays is concerned -- JPA spec says almost
nothing. The onus is on us as open source developers who have to figure out
what is a *good* way. If the users accept it -- then we did a good job and
we can take our view to the experts of spec committee to make that view part
of a standard. Today where JPA spec stands is a testimonial to such effort
by Hibernate or Kodo and many others who built their software *without* a
spec guiding them what to do or what is the "right" way. In fact, it is they
who made today's JPA spec possible. That is why I said : "X spec says so..."
is a weak argument in a open source context.  

   

   

-----
Pinaki 
--
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