On Mon, Nov 23, 2009 at 5:57 PM, logicmoo@gmail.com wrote:

Ok even Allegro uses T and NIL for the Booleans.. which is why

...

CL-USER(17):  (jclass-of (jfield "java.lang.Boolean" "TRUE")) NIL NIL

was still correct.. I think the closer we stick with Allegro the better.

for future reference (to myself) to make a boolean one does:

CL-USER(21): (jnew  (jconstructor "java.lang.Boolean" "java.lang.String") "True") #<java.lang.Boolean true {44AC5E}> CL-USER(22): (jclass-of (jnew  (jconstructor "java.lang.Boolean" "java.lang.String") "True")) "java.lang.Boolean" "java.lang.Boolean"

If you want a boolean (primitive type) I believe you can do (make-immediate-object T-or-NIL :boolean) If you want Boolean.TRUE or Boolean.FALSE the cleaner way would be to have a jfield-raw like jcall-raw, if I understand it correctly.

If there is any action items out of all this:

Perhaps:    javaInstance()    on Nil  returns Boolean.FALSE?

This would break a lot of existing code, I'm afraid. NIL is often used to mean null.

Then in Symbol.java

Object javaInstance() {         if (this == T) return Boolean.TRUE;         return super.javaInstance();    }

I don't agree for consistency with NIL and for similar concerns on existing code. However, hold on...

And in LispObject itself any thoughts on?

LispObject.this.javaInstance(Class c) {          if (c.isInstance(this)) return this;       // widen and resubmit for subclasses          if (c==int.class) return javaInstance(Integer.class);          if (c==boolean.class) return javaInstance(Boolean.class);       // they requested a boolean.. give it to them          if (c==Boolean.class) return getBooleanValue();       .....          //hit the error logic    }

Now for javaInstance(Class) I completely agree with you: it should mean - everywhere! - "convert this object to a Java object of the given class, if possible".

So LispObject.javaInstance(Class c) should be like you said, and in some subclasses (Fixnum, AbstractString come to my mind) it should be overridden. At that point we could even generify it:

public <T> T javaInstance(Class<T> c)

So users might write, e.g., String s = myLispObject.javaInstance(String.class);

Just my €.02

Alessio

----- Original Message ----- From: dmiles@users.sourceforge.net To: "Armed Bear" armedbear-devel@common-lisp.net Sent: Monday, November 23, 2009 7:42 AM Subject: Re: [armedbear-devel] SETF for JFEILDS

...

These 3 look good

CL-USER(2): (jclass-of (jfield "java.lang.System" "out")) "java.io.PrintStream" "java.io.PrintStream"

CL-USER(4): (jclass-of 1) NIL NIL

CL-USER(5): (jclass-of (make-immediate-object 1)) "java.lang.Integer" "java.lang.Integer"

But is this correct?

CL-USER(17):  (jclass-of (jfield "java.lang.Boolean" "TRUE")) NIL NIL CL-USER(18): (jclass-of (jfield "java.lang.Boolean" "FALSE")) NIL NIL

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