----- Original Message ----- From: "Alessio Stalla" alessiostalla@gmail.com To: dmiles@users.sourceforge.net Cc: "Armed Bear" armedbear-devel@common-lisp.net Sent: Monday, November 23, 2009 9:18 AM Subject: Re: [armedbear-devel] SETF for JFEILDS

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

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

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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)

(make-immediate-object t :boolean) #<java.lang.Boolean true {1C904F75}>

Neat, I hadn't known (or forgot) about Arg2 of #'make-immediate-object ! Thx

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.

CL-USER(24): (jfield-raw "java.lang.Boolean" "TRUE") #<java.lang.Boolean true {465098F9}>

Indeed.

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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.

*nod* well either meaning is just as dubious.. but as you say allot of existing code likes NIL to mean EMPTY which sounds more like a 'null' than a 'false'.

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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...

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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.

Good

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);

I like the generics for it as well

Just my €.02

Alessio

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----- 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

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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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