[armedbear-devel] Question about calling Java

[Mark Evenson]

Usually, I can find a way to translate given Java code into the ABCL 
equivalent.  Sometimes it takes quite a while to figure the correct 
syntax  which I attribute to the organically evolved nature of our Java 
integration, but I have never found something ultimately unexpressable. 
  Until now, although I think this has to do with me trying to debug 
ABCL internals with the ABCL REPL, but I want to document it.  Have I 
missed some way of making this call?

The code:

	SimpleString h = new SimpleString("FOO");
	Pathname.LOGICAL_PATHNAME_TRANSLATIONS.get(h));

LOGICAL_PATHNAME_TRANSLATIONS is a EqualHashTable object whose signature 
of get() is
	
	LispObject get(LispObject key)


This fails
	
	(jcall "get"
	  (jfield "org.armedbear.lisp.Pathname"
		  "LOGICAL_PATHNAME_TRANSLATIONS)
	  (jnew "org.armedbear.lisp.SimpleString" "FOO"))

with the error

   The value "org.armedbear.lisp.SimpleString" is not of type JAVA-OBJECT

Diving into the code shows that the Java.translateMethodArguments() call 
is always going to translate the SimpleString argument into a instance 
of  java.lang.String as this is what SimpleString.javaInstance() 
returns.  Is there any way to tell JCALL not to perform such translation 
on its arguments?  JCALL-RAW doesn't convert its return value, but maybe 
we need a JCALL-NAKED that doesn't translate its arguments?  I suspect 
that we don't need JCALL-NAKED for anyone not using Java objects that 
are descendents of org.armedbear.lisp.LispObject but I'm not exactly 
sure how to prove this claim.

-- 
"A screaming comes across the sky.  It has happened before, but there
is nothing to compare to it now."