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RE: [cross-project-issues-dev] Java 1.5

For a discussion on compiling with generics to 1.4 binaries:
https://bugs.eclipse.org/bugs/show_bug.cgi?id=107783

-Randy



                                                                           
             Ed Merks                                                      
             <merks@xxxxxxxxxx                                             
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             10/06/2006 08:25          RE: [cross-project-issues-dev] Java 
             AM                        1.5                                 
                                                                           
                                                                           
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Jeff,

The implications moving forward are very clear and somewhat unfortunate,
though perhaps not quite as black and white as your statement.   Also,
since a layering approach was not applied in the JDK in order to templatize
the Collection API, it's not clear how that could be made to work.   We'd
need two versions of EList, BasicEList, EMap, BasicEMap,
DelegatingListImpl, NotifyingListImpl, EcoreEList, and so on, not to
mention APIs such as Ecore itself.  Given three developers doing all the
development, the undertaking is already a stretch.  In any event, the
intent is that clients should be able to compile with 1.4 compatibility and
produce 1.4 .class files that will run with an EMF 2.2 runtime on a 1.4
JVM, so clients will still have much room to choose what's appropriate for
them.  After all, using older JVMs is how Java deals with this, so using
older EMFs seems an analogous approach; in necessary we can provide an EMF
2.3 (with only the bare minimum changes needed to integrate with Eclipse
3.3).  It may also be possible to compile the EMF 3.0 code base to produce
1.4 binaries so that we would provide a stand-alone 1.4 runtime as well as
a stand-alone 5.0 runtime.  Isn't there a compiler option and JSR for
compiling 5.0 source down to 1.4 binaries?

We can discuss these issues at the Achitecture Council meeting next week
(just as these issues were discussed with all the leads of the top level
projects in Chicago a few months ago).


Ed Merks/Toronto/IBM@IBMCA
mailto: merks@xxxxxxxxxx
905-413-3265  (t/l 969)



                                                                           
 Jeff McAffer/Ottawa/IBM@IBMCA                                             
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Ed,

So just to be clear, you are writing off a large number of EMF use
cases/scenarios as a result of this move.  EMF will not be usable on mobile
or reduced JRE clients.  Since there is an increasing (though still small)
move for people to use their components in several different scenarios, EMF
may well be ruled out as a candidate solution across the larger ranges that
need to accomodate the lowest common denominator.

I don't really know what you are doing but do wonder whether or not this
could be layered or structured such that you could get the Java5 use you
seek but do not force it on all EMF consumers.

Meta-statement  the Europa team as a whole needs to try and set some
direction here.  For example, if BIRT uses EMF and EMF moves to Java 5,
well BIRT is now ruled out of an additional range of usecases.

Jeff

                                                                           
 Ed Merks/Toronto/IBM@IBMCA                                                
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Doug,

EMF is in a bit of an odd position in that it provides and uses it own
runtime.  So unlike the JDT, which can target any JVM and hence can support
Java 5.0 without using Java 5.0 itself, EMF must target its own runtime.
For example, org.eclipse.emf.common..util.EList which extends
java.util.List to add move methods needs to be templatized just as is List
itself and similarly the implementation class
org.eclipse.emf.common.util.BasicEList needs to be fully templatized.  As
such, the org.eclipse.emf.common plugin will depend on Java 5.0 and since
all the rest of EMF depends on this, all the rest of EMF will be bound by
that decision; and of course we'll want to regenerate the Ecore API to
support Java 5.0.  So EMF 3.0 will absolutely not run on a 1.4 VM (which is
why we are moving to EMF 3.0 rather than EMF 2.3, even though we hope to
provide a binary compatible runtime capable of running 2.2-based code
without recompilation).  It's a huge undertaking for our tiny team, given
that there is little experience in this domain from which we can draw.  I'm
finding that templatizing collection APIs is shockingly complicated (even
though using templatized APIs is usually rather simple and nice).


Ed Merks/Toronto/IBM@IBMCA
mailto: merks@xxxxxxxxxx
905-413-3265  (t/l 969)

                                                                           
 Doug Schaefer <DSchaefer@xxxxxxx>                                         
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Thanks, Ed. I was thinking more about the runtime for your plug-ins. Will
EMF 3.0 run on a 1.4 VM?

Doug Schaefer
QNX Software Systems
Eclipse CDT Project Lead
http://cdtdoug.blogspot.com








From: cross-project-issues-dev-bounces@xxxxxxxxxxx
[mailto:cross-project-issues-dev-bounces@xxxxxxxxxxx] On Behalf Of Ed Merks
Sent: Thursday, October 05, 2006 10:23 AM
To: Cross project issues
Subject: Re: [cross-project-issues-dev] Java 1.5


Doug,

Supporting and exploiting Java 5.0 is the main development item for EMF
3.0.   We hope to make generating the 5.0 features optional and to ensure
that generated code can compile and run against the 2.2 EMF runtime so that
folks needing support for Java 1.4 will be able to achieve that.


Ed Merks/Toronto/IBM@IBMCA
mailto: merks@xxxxxxxxxx
905-413-3265  (t/l 969)


                                                                           
 Richard Gronback                                                          
 <richard.gronback@xxxxxxxxxxx>                                            
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GMF is using 1.5 language features for this release.

- Rich


On 10/5/06 10:13 AM, "Doug Schaefer" <DSchaefer@xxxxxxx> wrote:

Hey gang, I’m just wondering if any of the projects participating in Europa
are planning on dropping support for Java 1.4, i.e. are planning on using
Java 1.5 features.

Doug Schaefer
QNX Software Systems
Eclipse CDT Project Lead
http://cdtdoug.blogspot.com







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Richard C. Gronback
Borland Software Corporation
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