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From "Matthew T. Adams" <matthew.ad...@xcalia.com>
Subject Remove pm.attachCopy? (was: RE: RETRY: Transient instance referencing a detached instance? (was: Question about attachCopy, transient & detached instances))
Date Mon, 17 Oct 2005 19:07:11 GMT
I like the convergence in the api, and I also like the suggestion to return
the root object(s) from makePersistent, as it increases symmetry.

Could attachCopy and makePersistent become one, just makePersistent?  The
only difference in the proposal as you suggest, Craig, is the handling of
transient instances.  attachCopy copies instances and makes the copies
persistent-new, whereas makePersistent just makes them persistent-new; all
other behavior is the same.  If we got rid of attachCopy, in favor of
makePersistent, and changed makePersistent such that it returns the root
object(s) given, then the behavior is covered, except for attachCopy's copy
semantic for transient instances.  The only difference in the API if we keep
attachCopy is the copy semantic for transient instances, which I don't think
is all that important.

Thoughts?

--matthew


>-----Original Message-----
>From: Craig.Russell@Sun.COM [mailto:Craig.Russell@Sun.COM] 
>Sent: Sunday, October 16, 2005 12:26 PM
>To: JDO Expert Group; jdo-dev@db.apache.org
>Subject: Re: RETRY: Transient instance referencing a detached 
>instance? (was: Question about attachCopy, transient & 
>detached instances)
>
>
>Javadogs,
>
>I've reviewed this material and agree with the general conclusion,  
>that we can add the ability to include detached objects in the  
>closure of instances for both makePersistent and attachCopy.
>
>The spec as of today requires treating these three types of objects  
>in the closure differently:
>
>persistent instances
>
>attachCopy throws an exception; makePersistent ignores them
>
>transient instances
>
>attachCopy copies them and creates persistent-new instances;  
>makePersistent makes them persistent-new
>
>detached instances
>
>attachCopy copies them; makePersistent throws an exception
>
>Here's the change as I would propose it:
>
>persistent instances
>
>attachCopy ignores them; makePersistent ignores them
>
>transient instances
>
>attachCopy copies them and creates persistent-new instances;  
>makePersistent makes them persistent-new
>
>detached instances
>
>attachCopy copies them; makePersistent copies them
>
>If we make this change, the behavior of makePersistent and attachCopy  
>are more similar than today. The differences are in the treatment of  
>transient instances and whether or not the root objects are returned.  
>If we like, we can have makePersistent also return the root objects  
>by making a source-compatible change to the signatures of  
>makePersistent.
>
>Craig
>
>On Oct 5, 2005, at 11:59 AM, Matthew T. Adams wrote:
>
>> "Wes Biggs" <wes@tralfamadore.com> wrote in message
>> news:<mailman.5533.1128524276.10966.jdo-general@jdo-experts.org>...
>>
>>> Would it be cleaner to not allow transient instances to be  
>>> included in
>>> attachCopy() graphs at all?  Sounds that way to me.
>>>
>>>
>> No, I'd like to continue to allow transient instances to be  
>> included in
>> attachCopy graphs.  I'd like to **add** the ability for detached  
>> objects to
>> be included in makePersistent graphs.
>>
>> This use case fell out very naturally for me while working on a  
>> website that
>> uses detached objects.  I ended up with a transient User object  
>> referencing
>> a detached Country object, and, of course, when I called
>> pm.makePersistent(user), I got an JDOUserException as I should  
>> have, per the
>> spec as it stands right now.
>>
>> --matthew
>>
>>
>>
>
>



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