problem with vargs method

[Jim Laskey]

Worked okay for me.  So must be addressed in a later release. :-/
 


On 2012-02-07, at 1:17 PM, Jochen Theodorou wrote:

> 
> That will produce a
> 
> java.lang.invoke.WrongMethodTypeException: (Ljava/lang/Object;[Ljava/lang/Object;)V cannot be called without a receiver argument as ([Ljava/lang/Object;)Ljava/lang/Object;
> 
> imho casting to Object and Object[] in
> 
> mh.invokeExact((Object)Class.class, (Object[])new Class[0]);
> 
> is without effect, since invokeExact is a vargs method an everything will just be put into an Object[] anyway. We had not a compiler change for this kind of thing, had we?
> 
> bye Jochen
> 
> Am 07.02.2012 17:52, schrieb 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
>>> 
>> 
> 
> 
> -- 
> 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
>