Re: [xmlvm-users] Compile errors in Obj/C code for inner classes

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

that is a known deficiency of XMLVM. Currently, we cross-compile Java to 
Objective-C making use of Objective-C's object model. Unfortunately, 
Objective-C does not permit to re-define a member variable in derived 
classes. That means, you cannot write a Java program that does that 
(although we name mangle the member's type into its name so at least we 
support same member name with different types along an inheritance 
path). Ordinarily you can easily avoid this by simply refactoring your 
program. Until I saw your message, I didn't know that javac itself 
creates this pattern.

Unfortunately there is no easy solution. To add proper member lookup in 
Objective-C would incur a major runtime overhead. That is one of the 
reasons I want to change XMLVM's backend to C because here we are in 
control of how to implement Java's object model and don't try to map a 
statically object model to a dynamically typed one.

Sorry for the long-winded explanation. For now, I suggest you don't use 
inner classes the way you do and way until we have the new C backend 
(which will take a while to complete).

Arno


On 6/22/10 1:29 PM, Markus Heberling wrote:
> Hi,
>
> Converting the following class from java to objc generates wrong objc code.
>
> public class Main extends UIApplication {
>
> public void applicationDidFinishLaunching(UIApplication app) {
> //...
> }
>
> public static void main(String[] args) {
> UIApplication.main(args, Main.class);
> }
>
> public abstract class AbstractTest{
>
> }
>
> public class Test1 extends AbstractTest{
>
> }
>
> public class Test2 extends AbstractTest{
> }
> }
>
> I get this in the Objc .h file for AbstractTest
> @interface mylib_Main_AbstractTest : MyObject
> {
> @public mylib_Main* this_0_mylib_Main;
>
> }
>
> this for Test1
> @interface mylib_Main_Test1 : mylib_Main_AbstractTest
> {
> @public mylib_Main* this_0_mylib_Main;
>
> }
>
> and this for Test2
> @interface mylib_Main_Test2 : mylib_Main_AbstractTest
> {
> @public mylib_Main* this_0_mylib_Main;
>
> }
>
> So the reference back to the enclosing class is generated in each of
> this @interface declarations. This gives compile errors in both
> mylib_Main_Test1 and mylib_Main_Test2:
> /Users/markus/Documents/workspace/xmlvm/test/src/xcode/trim/mylib_Main_Test1.h:15:0
> /Users/markus/Documents/workspace/xmlvm/test/src/xcode/trim/mylib_Main_Test1.h:15:
> error: duplicate member 'this_0_mylib_Main'
>
> Is it possible to fix xmlvm to generate better code for such java
> constructs?
>
> Regards,
> Markus
>
>
>
>
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