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From: Peter Lane <>
Subject: building int[] arrays at runtime
Date: Wed, 01 Feb 2017 23:12:00 -0000	[thread overview]
Message-ID: <> (raw)

Hi list,

I've been using Kawa as an R7RS implementation for a little while, and 
now am using Kawa to work with a Java library.  I've hit a little 
irritant when calling overloaded methods in Java.

If I build an int[] at runtime, I get a warning about more than one 
applicable method.  The code seems to run and give the right result, so 
the runtime does the right thing.  As the warning always appears first, 
when the script is loaded, I assume the script is compiled on loading 
and so the problem is discovered.

I understand why I'm getting this warning, but wondered if:

a. I should do something other than (apply int[] (list 3)) to create an 
int[] at runtime
b. Can I put a compile-time type hint in, to appease/suppress the 
initial checks?

I can turn the warnings off with: --warn-invoke-unknown-method=no
but that hides other potential problems, like a mis-spelt method name, 
until they trip a runtime exception.

Below is a simple example of what I'm doing:

Java class
public class Class1 {

   public void show (int[] x) {
     System.out.println ("show " + x[0]);

   public void show (String s) {
     System.out.println ("show " + s);

Kawa script
(define *x* (Class1:new))
(*x*:show "me")
(*x*:show (int[] 3))
and all is fine, I get the expected output:

$ kawa test.scm
show me
show 3

The problem arises when I try building the array at runtime:

(define *x* (Class1:new))
(*x*:show "me")
(*x*:show (apply int[] (list 3))); <----- built at runtime

$ kawa test.scm
test.scm:3:1: warning - more than one possibly applicable method 'show' 
in Class1
   candidate: void
   candidate: void[])
show me
show 3



Peter Lane

             reply	other threads:[~2017-02-01 23:12 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-01 23:12 Peter Lane [this message]
2017-02-01 23:41 ` Per Bothner
2017-02-02 18:43   ` Peter Lane
2017-02-01 23:45 ` Per Bothner

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