Re: [xmlvm-users] Using categories vs. encapsulation in Objective-C compat-lib

[Arno P. <ar...@pu...>]

Apple recently added something called Associative References that might 
help with what you need:
http://developer.apple.com/iphone/library/documentation/cocoa/Conceptual/ObjectiveC/Articles/ocAssociativeReferences.html

Arno


On 7/12/10 7:22 AM, Paul Poley wrote:
> Regarding categories & cross-compiling the original JRE classes, I am
> trying to implement:
>
> wait()
> wait(long)
> notify()
> notifyAll()
>
> 1) If cross-compiling the original JRE, we will of course still need to
> implement the native methods, including java.lang.Object's wait/notify
> 2) Unfortunately my implementation of wait/notify requires me to keep
> some state in java_lang_Object & I cannot do so since it is a category.
>   Is there a way around this in XMLVM's current state?
>
> I believe I have everything written out, although it's a theoretical
> solution right now.  However, because I need member variables, I cannot
> try it out without changing java_lang_Object to inherit from NSObject
> rather than be a category.  That causes other issues though.  For
> example, many XMLVM objects represented as categories of objective-c
> objects automatically share the benefits of java_lang_Object without
> explicitly saying so, as needed.  Using inheritance for java_lang_Object
> instead of categories removes this currently necessary benefit.
>
> Does anyone have any suggestions?  If we can get that working,
> implementing Thread interruptions shouldn't be very difficult building
> upon this.
>
> Thanks!
> Paul Poley
>
>
> On Sun, Jul 11, 2010 at 6:47 AM, Arno Puder <ar...@pu...
> <mailto:ar...@pu...>> wrote:
>
>
>     there are always trait-offs when you map from one platform to another.
>     The efficiency of using categories comes with the downside you've
>     described.
>
>     We are currently working on cross-compiling the original JRE classes
>     from OpenJDK. For one, it would give us instant 100% compatibility and
>     the issues you have described would also be resolved. Note that this is
>     ongoing work and will take some time to complete.
>
>     Arno
>
>
>     On 7/7/10 7:31 PM, bar...@ao... <mailto:bar...@ao...> wrote:
>      >
>      > I think that having java_util_ArrayList.m be a category on
>      > NSMutableArray is a clever use of categories, but wouldn't
>     encapsulation
>      > generally be a more flexible option? One potential issue I see
>     with the
>      > category approach is that since java_util_ArrayList.m and
>      > java_util_LinkedList.m are both categories on NSMutableArray, what
>      > happens if the client java code relies on checking the kind of
>     the list
>      > using reflection? Won't java_util_ArrayList and java_util_LinkedList
>      > then be indistinguishable from each other at runtime?
>      >
>      > The same goes for the other classes where categories are used:
>     String,
>      > StringBuffer, HashMap/Set, URI/URL, etc.
>      >
>      >
>      >
>      >
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