two things invokedynamic canbot do

[Jochen Theodorou]

Am 26.06.2012 11:59, schrieb Rémi Forax:
> On 06/26/2012 11:40 AM, Jochen Theodorou wrote:
>> Hi all,
>>
>> just to be sure I understand correctly... afaik there are two things
>> invokedynamic cannot do.
>>
>> (1) calling private methods
>> actually I am not sure this is really true. There is a Lookup instance I
>> can use to get handles to private methods (afaik), therefore it should
>> be possible. Or is there an artificial restriction of some kind?
>
> No restriction, or you need a way to get the proper lookup
> or you use reflection to get a j.l.r.Method, call setAccessible(true)
> and unreflect it as a MethodHandle (see MethodHandles.unreflect*).

ok, so I can remove those stupid helper methods ;)

>> (2) calling super()
>> afaik I cannot generate a call site that replaces the invokeSpecial call
>> to a super class constructor.
>
> You can call super.foo()

ah true... this is not reflection.. even if I get the handle from the 
super class it won't call the overriding method in the current class. I 
totally forgot... how do you handle this in your backport?

 > but not super().
> It's because the VM verifies that you should not have access to an
> uninitialized object, ie. access to an object before calling super().
> So if you do a super() using a MethodHandle, because it's hidden
> by an invokedynamic (or a constant method handle) the VM as no
> way to know that this invokedynamic will call the constructor
> of the super class, so the verifier will not let you call invokedynamic
> on this in a constructor without calling explicitly super() before.

I see... that is a bit unfortunate. I have to do quite some tricks to 
enable the super constructor call according to Groovy rules for method 
dispatch. And what I do I won't call fast.

bye blackdrag

-- 
Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
blog: http://blackdragsview.blogspot.com/
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