Issue 1752:  mapping of IDL enumerations to java (java-rtf)
Source:  (, )
Nature:  Revision
Severity:  Significant
Summary: Summary: he current mapping of IDL enumerations to Java relies on there being
 one and only one instance of an enum.  The instance is held as
 a static variable in the enumeration class.  Since there is only
 one instance, identity comparisons are used in comparing enums and
 the enumeration value class does not implement equality or hash
 methods based on the value of the enum.
 

Resolution: Close, no action
Revised Text: 
Actions taken:
July 29, 1998: received issue
June 4, 1999: closed issue
Discussion: 

End of Annotations:=====
Return-Path: <www>
Date: Wed, 29 Jul 1998 13:43:59 -0400
From: www
To: juergen@omg.org, web-incoming@omg.org
Subject: WWW Form output

Name: Bruce Schuchardt
Company: GemStone
Email: bruce@gemstone.com
Notification: Yes
Specification: Mapping of OMG IDL to Java
Section: 23.6
Formal #: 98-01-16
Version: 2.2
Revision_Date: December 1997
Page: 14
Nature: Revision
Severity: Significant
full_desc: The current mapping of IDL enumerations to Java relies on
there being
one and only one instance of an enum.  The instance is held as
a static variable in the enumeration class.  Since there is only
one instance, identity comparisons are used in comparing enums and
the enumeration value class does not implement equality or hash
methods based on the value of the enum.

This assumption appears to fail if the enumeration value class is
garbage collected in the course of execution.  When the value
class is reloaded, new objects are created and placed in the static
variables holding the enum instances.  These new objects do not
have the same hash values as the previous enum instances, and
comparisons
fail to work.

Another scenario where we've seen this problem arise is in an
application that is storing enum objects in a persistent object
store and later comparing them with the objects in the enumeration
value class at runtime.  Unless the class and its static variables
are also made persistent, the unique enum value scheme falls apart.
The class gets loaded by the Java VM and new enum objects are created.
These are later compared with persistent enum objects by the
application
and the comparisons fail.

Please consider revising the mapping of enums to require generation
of equality and hash methods that are class and value based.
Application
developers should then be advised to use equals() when comparing
enum objects.

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