[armedbear-devel] Integration of CL and Java

[Anton Vodonosov]

Hello,

on Saturday, August 1, 2009, 1:18:53 AM Tobias wrote:

>   Long term:
>   [...]
>     * Make it possible to extend Java classes from Lisp.
>     * Make it possible to implement Java interfaces from Lisp.

It is possible already, with JAVA:JNEW-RUNTIME-CLASS, although maybe
the form isn't really convenient.

To have JAVA:JNEW-RUNTIME-CLASS in ABCL it is necessary to compile
org/armedbear/lisp/runtime-class.lisp. It requires asm.jar [1] to be in
classpath, and therefore, as far as I understand, is excluded from
compilation by default (see <exclude
name="org/armedbear/lisp/runtime-class.lisp"/> in build.xml).

Another interesting source that may be useful to define convenient
java interop is port of Rich Hickey's Jfli [2] to ABCL. I found the
ABCL version created by asimon at math.bme.hu here:
http://www.math.bme.hu/~asimon/lisp/jfli-abcl.tar.

jfli-abcl provides a macro (experimental) NEW-CLASS macro for
creation java classes in Lisp (including inheritance from existing
classes/interfaces). NEW-CLASS is a wrapper around
JAVA:JNEW-RUNTIME-CLASS. Some examples of it's usage are also
provided.

I'd say NEW-CLASS macro isn't perfect from usability point of view,
but may probably be used as a starting point for something better.

>    * integrate Java's object hierarchy into the CLOS object
>      hierarchy. I'm not a CLOS expert, but a few people come to mind
>      who to ask.

Jfli approaches this problem: http://jfli.sourceforge.net/#wrappergen

I am using these tools now to create a plugin for for Intellij IDEA
(nothing serious, more like a hello world). Maybe I'll post it
as an example to the list soon.

In the attach is the jfli-abcl.lisp I use. It fixes small error in
the NEW-CLASS (one backqoute :). And adds a kind of extension/fix:
constructors for NEW-CLASS created classes may accept not only jfli
wrapped java objects, but also native Lisp objects (which are java
objects anyway in case of ABCL).

1. ASM java bytecode manipulation framework home is here: http://asm.ow2.org/
   ABCL seems to use not the latest one, but elder 1.5.3 version:
   http://forge.ow2.org/project/download.php?group_id=23&file_id=3084

2. http://jfli.sourceforge.net/

Best regards,
- Anton
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