RE: [Foil-users] generic methods

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 >This wouldn't work for me. I want to and have written code that 
 >is general, I mean where the type of the object is not known or could
change.

Ok. Are the functions you are calling polymorphic in Java - i.e. are they
members of base classes or interfaces? Or are you just rolling your own
name-based polymorphism?

If the former, you can (and should, given your objectives) just use the most
general class in the function call. E.g. if SetText is a method of Control,
and Control is a base class/interface of Combo, and you want to write code
not specific to Combo, you can simply say:

(control.settext my-combo "foo")

You don't need to make the call in the specific class of the object (i.e.
combo.settext)- it will be resolved by the Java virtual function mechanism
to the right SetText for the actual type of the object (Combo in this case).

If you want name-based polymorphism I can't help you.

The bottom line is if the code emitted by your macro doesn't contain
Foil-generated symbols, then Clojure won't generate Java calls for you.

- -----Original Message-----
From: foi...@li...
[mailto:foi...@li...] On Behalf Of Francis
Leboutte
Sent: Friday, June 17, 2005 9:32 AM
To: foi...@li...
Subject: RE: [Foil-users] generic methods

At 17/06/2005 15:33, Rich Hickey wrote:
>If you ever intend to use Clojure,

Very probably.

>I would definitely recommend against
>this.
>
>Performance isn't really the issue - Foil performance is dominated by 
>the socket interaction and almost nothing you do on the Lisp side matters.
>
>The problem is that you are removing the symbols that Clojure will need 
>to compile the code. It leverages the reflection info connected to the 
>symbols combo.settext, button.settext etc in order to generate typed 
>reflection-free calls when compiled. Clojure has no provisions for
reflection-based calls.

I don't really understand. Do you meanI shouldn't use symbols like settext
or setfont to define functions?

>I hope you are using an editor with symbol completion,

of course, without symbol completion, it would be too hard 
:-)  At present time I have access to 17262 symbols, most of them 
in the |org.eclipse.swt*| and |com.nwoods.jgo| packages. I also 
use a lot a specific apropos function that looks only in the java packages.

>which should make
>this less of a bother, but if it's still a pain I recommend a macro that
>does something like
>
>(with-members-of (swt-control combo.)
>         (.settext "foo")
>         (bar baz)
>         (.somethingelse x y z))
>
>which expands into:
>
>(progn
>         (combo.settext swt-control "foo")
>         (bar baz)
>         (combo.somethingelse swt-control x y z))

This wouldn't work for me. I want to and have written code that 
is general, I mean where the type of the object is not known or could
change.

By the way, in the same vein, I have also defined apply-j-method 
that doesn't require to define a new function. Examples:

(apply-j-method "SETFOCUS" control)
(apply-j-method "SETDEFAULTBUTTON" shell button)

I hope I could use this and Clojure.

Francis

>I've been meaning to add something like with-members-of to Foil, but
haven't
>yet had the time.
>
>I have to say I consider the "complete-ability" of Foil symbols to be an
>important feature, vs. say the Javadot notation of JScheme et al.
>
>
>-----Original Message-----
>From: foi...@li...
>[mailto:foi...@li...] On Behalf Of Francis
>Leboutte
>Sent: Friday, June 17, 2005 3:08 AM
>To: foi...@li...
>Subject: [Foil-users] generic methods
>
>Hello
>
>In order to be able to write
>(settext swt-control "hello")
>
>instead of
>(combo.settext swt-control "hello")
>(button.settext swt-control  "hello")
>...
>
>I have defined a macro to define "generic java methods" like this:
>
>(def-java-generic "SETTEXT")
>
>This call expands in:
>
>(progn
>    (export 'settext)
>    (defun settext (object &rest rest)
>      (ensure-typed-ref object)
>      (if object
>          (let* ((fun-name (concatenate 'string (symbol-name (type-of
>object)) "SETTEXT"))
>                 (fun (find-symbol fun-name)))
>            (unless (and fun (fboundp fun))
>              (error "can't find function definition of settext for ~s
>object" object))
>            (apply fun object rest))
>        (error "settext doesn't accept nil as first argument"))))
>
>
>Are they potential pitfalls in this?
>Performance maybe? Instead of ensure-typed-ref, is there some
>other function to use that would be less costly (just the class
>name is needed, not the conversion of the fref to this class).
>
>Francis
>
>
>
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