Re: blog entry - Kawa in Computer Languages "shootout"

[Jamison Hope <jrh at theptrgroup dot com>]

On Oct 22, 2010, at 12:00 AM, Per Bothner wrote:

> On 10/20/2010 03:01 PM, Jamison Hope wrote:
> > Here's a chameneos-redux implementation.

> I also updated the "shootout" blog entry:
> http://per.bothner.com/blog/2010/Kawa-in-shootout/


I'm working on meteor-contest, but I'm getting compilation errors.  
I've whittled it down to the following, which works fine from the  
REPL. The problem seems to be when one class has, as a field, an array  
of elements of another class defined in the same module.

$ cat meteor.scm
> (define-simple-class P ())
>
> (define-simple-class S ()
>   (pieces :: P[] init: (P[] length: 10))
>
>   ((clone2) :: S
>    (let ((s :: S (S)))
>      (do ((i :: int 0 (+ i 1)))
>          ((= i pieces:length))
>        (set! (s:pieces i) #!null)) ;;<- NPE here
>      s)))

Interactively:

$ rlwrap java kawa.repl
> #|kawa:1|# (load "meteor.scm")
> #|kawa:2|# ((S):clone2)
> S@7546c1d4


but when I try to compile:

$ java kawa.repl --main -C meteor.scm
> (compiling meteor.scm to meteor)
> meteor.scm:10:8: caught exception in inline-compiler for #<procedure  
> field> - java.lang.NullPointerException
>     gnu.bytecode.ArrayType.getReflectClass(ArrayType.java:69)
>     gnu.kawa.reflect.SlotGet.compile(SlotGet.java:291)
>     gnu.expr.ApplyExp.inlineCompile(ApplyExp.java:587)
>     gnu.expr.ApplyExp.compile(ApplyExp.java:174)
>     gnu.expr.ApplyExp.compile(ApplyExp.java:111)
>     gnu.expr.Expression.compile(Expression.java:166)
>      
> gnu.kawa.reflect.CompileArrays.compileArraySet(CompileArrays.java:74)
>     gnu.kawa.reflect.CompileArrays.compile(CompileArrays.java:49)
>     gnu.expr.ApplyExp.inlineCompile(ApplyExp.java:587)
>     gnu.expr.ApplyExp.compile(ApplyExp.java:174)
>     gnu.expr.ApplyExp.compile(ApplyExp.java:111)
<snip>

The compiler seems to be unaware of the type of the elements of  
s:pieces (which should be P). The exception is from  
elClass.getClassLoader(), where elClass is elements.getReflectClass().

As further evidence of this being the problem, the following compiles  
but fails at runtime:

$ cat test.scm
> (define-simple-class A ())
>
> (define-simple-class B ()
>   (a :: A[] init: (A[] length: 2)))
>
> (define b :: B (B))

$ java kawa.repl --main -C test.scm
> (compiling test.scm to test)

$ java test
> Exception in thread "main" java.lang.ClassFormatError: Field "a" in  
> class B has illegal signature "[null"
> 	at java.lang.ClassLoader.defineClass1(Native Method)
> 	at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
> 	at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
> 	at  
> java.security.SecureClassLoader.defineClass(SecureClassLoader.java: 
> 141)
> 	at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
> 	at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
> 	at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
> 	at java.security.AccessController.doPrivileged(Native Method)
> 	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
> 	at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
> 	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
> 	at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
> 	at test.<clinit>(test.scm)


By the way, thank you for the changes in r6772. I don't remember if I  
had requested that, but I know I had thought of it as a "wouldn't it  
be nice if…" as I started to look through some of the classes I have  
without no-argument constructors.

-Jamie

--
Jamison Hope
The PTR Group
www.theptrgroup.com