Re: Receiver class does not define or inherit an implementation of the resolved method

[Phil Eaton <phil@eatonphil.com>]

I spoke too soon. The issue is that I truly do need both of these methods
to be called `apply` not `apply` and `apply$1`.

For what it's worth this kind of redefinition of the same method worked for
me in ABCL lisp. So I know it's definitely possible to express in Java.

On Mon, Aug 30, 2021 at 7:09 PM Phil Eaton <phil@eatonphil.com> wrote:

> Aha! It gave my second apply method a different suffix. By reordering
> these two methods the whole thing somehow works.
>
> $ javap main\$0.class
> Compiled from "main.scm"
> public class main$0 implements io.jooby.Route$Handler {
>   main$frame this$0;
>   public java.lang.CharSequence apply(io.jooby.Context);
>   public java.lang.Object apply$1(io.jooby.Context);
>   public main$0(main$frame);
> }
>
>
> It's weird but I'll take it.
>
>
>
> On Mon, Aug 30, 2021 at 12:40 PM Per Bothner <per@bothner.com> wrote:
>
>> On 8/29/21 12:03 PM, Phil Eaton wrote:> Still new to Kawa. I'm trying to
>> implement an interface (
>> > io.jooby.Route$Handler
>> > <
>> https://github.com/jooby-project/jooby/blob/2.x/jooby/src/main/java/io/jooby/Route.java#L247
>> >).
>> > It only has a single non-default method, apply.
>> >
>> > Here's what I've got
>> >
>> > (define (route app method path handler)
>> >    (let ((handler (object (io.jooby.Route$Handler)
>> >                           #| This method exists just to stop Jooby from
>> > trying to introspect Java code that doesn't exist because this isn't
>> > written in Java. |#
>> >                           ((apply (ctx ::io.jooby.Context)) ::string
>> >                            #!null)
>> >                           ((apply (ctx ::io.jooby.Context))
>> > ::java.lang.Object
>> >                            (handler ctx)))))
>> >      (app:route method path handler)))
>> >
>> >
>> > But when this gets exercised, I get:
>> >
>> > [worker-1-3] ERROR io.jooby.Jooby - GET /hello-world 500 Server Error
>> > java.lang.AbstractMethodError: Receiver class main$0 does not define or
>> > inherit an implementation of the resolved method 'abstract
>> java.lang.Object
>> > apply(io.jooby.Context)' of interface io.jooby.Route$Handler.
>>
>> I don't see anything obviously wrong.  One thing to try is instead of an
>> anonymous class (with object) use a named class (with
>> define-simple-class).
>> The anonymous class is more convenient of course there is some extra
>> "magic"
>> (such as invisible fields) that might complicate things.
>>
>> > Also on a tangent, I was excited about the lambda shorthand for single
>> > method objects. Like I said this interface only has a single non-default
>> > method: apply. But I tried just calling `(app:route method handler)`
>> > without wrapping it in the io.jooby.Route$Handler object but it still
>> > failed. I guess it couldn't figure out this one method.
>>
>> Kawa has to be able to figure out at compile time that a specific
>> class/interface
>> is required before it can convert the lambda to an object.  (As far as I
>> can
>> remember, doing this conversion at run-time isn't implemented, and would
>> be
>> fairly complicated.)  So you may need to add some more type-specifiers.
>>
>> I suggest using javap to look at the generated classes, to see what is
>> going on.
>> --
>>         --Per Bothner
>> per@bothner.com   http://per.bothner.com/
>>
>