Hi, The only issue that I'm aware of that is related to this kind of change is >>> the requirement to recompile all the classes in the hierarchy when >>> making a >>> change [0]. If you don't do this its possible for an infinite recursion >>> and >>> eventual stackoverflow to occur. Now as far as I can tell the >>> entire hierarchy of Buffer classes are all either package scoped classes, >>> or they are public classes with package scoped constructors. So I'm not >>> aware of a way to sub class them without the code being part of the JDK. >>> This would mean that the subclasses all need to be recompiled, satisfying >>> the safety criteria. >>> >>> This is a long standing bug to look at this issue [1]. >> CharBuffer.subSequence >> was one case that was retrofitted in 7. As you note, buffers are not >> designed to >> be extended outside of the java.nio package so this should make a number >> of >> options possible. >> >> [1] https://bugs.openjdk.java.net/browse/JDK-4774077 >> > > Hi Richard, > > It looks to me like there are no obvious problems with changing the buffer > subclasses to use covariant overrides. As Alan mentioned, one API was > modified this way in 7, by Martin Buchholz. The discussion threads for this > change are [2] and [3]. It looks like Martin considered additional > covariant overrides, but ultimately backed off from this for a variety of > incidental reasons; see [4]. There is a certain amount of work here above > and beyond just changing the return types, but there don't appear to be any > fundamental issues. >
Thanks for the feedback guys - its most appreciated and I'll take a look through the detailed linked you provided. Ulf posted several links, but these seem mostly related to language change > proposals related to implicit method invocation chaining. I don't think > these proposals are active at the moment, so I'd suggest that you pursue a > library-only change. I had no intention in my original email to broaden the scope of this change to include changing the type system itself! I was only really thinking about a library level change, though I appreciate the links Ulf, thanks. regards, Richard Warburton http://insightfullogic.com @RichardWarburto <http://twitter.com/richardwarburto>
