Re: [Jython-dev] Support for interface default methods when selecting an overloaded method

[Jeff A. <ja...@fa...>]

Thanks for trying the RC.

Had it worked, it would have been luck. It has crossed my mind that it 
ought to be a feature, but we haven't attempted to add it. I haven't 
even thought about how default is implemented in Java.

You could raise it as a bug (feature request) on bugs.jython.org. You 
could even submit a patch. (The logic of method resolution is fairly 
complicated.) There will, I think, be a 2.7.3, and if there isn't, it 
will be because we're working on a 3.x. One of them should have this if 
it can be implemented at all.

Jeff Allen

On 05/03/2020 06:30, Nicolas Falliere wrote:
> Hello Jython Dev Team,
>
> Per 
> https://www.jython.org/jython-old-sites/archive/221/archive/22/userguide.html#overloaded-java-method-signatures: 
> /"Java methods are allowed to be overloaded for different signatures 
> (types and number of arguments). When different versions of the method 
> differ in the number of arguments that they expect, the appropriate 
> method can be easily determined from the number of arguments passed to 
> the method."/
>
> With Jyhon 2.7 (2.7.1, and the current RC of 2.7.2 as well), this 
> works fine for regular class methods, eg:
> class A {
>   void f(int a) {
>     return a + 1;
>   }
>   void f(int a, int b) {
>     return a+b;
>   }
> }
>
> in Jython:
> A().f(4)     # will select the proper overload
> A().f(1, 2)  # will select the proper overload
>
> However, for interfaces:
> interface I {
>   default void f(int a) {
>     return f(a, 1);
>   }
>   void f(int a, int b);
> }
> class A implements I {
>   void f(int a, int b) {
>     return a+b;
>   }
> }
>
> in Jython:
> x = someMethodReturningAnObjectImplementingI()
> x.f(4)     # fail, complains that method should receive 2 args
>
> So it looks like default methods, a language addition of Java 8, may 
> not be seen by the Jython interpreter. Is that the case, or am I doing 
> something wrong? In the former case, any chance to support that in a 
> coming release?
>
> Thank you & Best regards,
> --
> Nicolas Falliere (ni...@pn... <mailto:ni...@pn...>)
> JEB Decompiler, Founder and Architect
> PNF Software <https://www.pnfsoftware.com/>| Follow us on Twitter 
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