problem with vargs method

[Jim Laskey]

Try

       MethodType type = MethodType.methodType(Constructor.class, Class[].class);
       MethodHandle mh = MethodHandles.lookup().findVirtual(Class.class, "getDeclaredConstructor", type);
       MethodType target = MethodType.methodType(void.class, Object.class, Object[].class);
       mh = MethodHandles.explicitCastArguments(mh, target);
       mh.invokeExact((Object)Class.class, (Object[])new Class[0]);

Cheers,

-- Jim

On 2012-02-07, at 12:37 PM, Jochen Theodorou wrote:

> Am 07.02.2012 17:29, schrieb Jim Laskey:
>>>>>        MethodType type = MethodType.methodType(Constructor.class, Class[].class);
>>>>>        MethodHandle mh = MethodHandles.lookup().findVirtual(Class.class, "getDeclaredConstructor", type);
>>>>>        MethodType target = MethodType.methodType(Object.class, Object.class, Object.class);
>>>>>        mh = mh.asType(target);
>>>>>        mh.invokeWithArguments(Class.class,new Class[0]);
>> 
>> As soon as you  mh = mh.asType(target); it is no longer vararg, so it
>> is treating new Class[0] as the second argument cast to Object.  If
>> you are trying to type as (Object , Object[]). I think you are going
>> to run into difficulties validating (Class[]) Object[].  You may have
>> to add a wrapper to get what you want, but you could also try using
>> asCollector.
> 
> or in other words: I should not use invokeWithArguments for this.
> 
> If I wanted to use the same target type... since that is what my call site gives me... and I wanted to use invokeExact instead, how would I have to change the program?
> 
> bye blackdrag
> 
> -- 
> Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
> blog: http://blackdragsview.blogspot.com/
> german groovy discussion newsgroup: de.comp.lang.misc
> For Groovy programming sources visit http://groovy-lang.org
>