strange ClassFormatError with indy

[Jochen Theodorou]

Am 31.08.2012 01:22, schrieb John Rose:
[...]
to sum it up... JVMS 4.2.2 says it is not allowed, JVMS 4.4.6 kind of 
allows it...  the discussion in 4.10.1.4 says usages of <init> and 
<cinit> are not typesafe ...

> So if you want your code to pass the verifier, avoid <init> (and <clinit>).

ok, so it is the name after all, because <init> and <clinit> are not 
regular names at all. I was aware of the restriction of not being able 
to call "super()" in a constructor, but that this extends to not being 
able to do a "new ArrayList()" using no extra method name argument, is 
new to me... Why is that? Because the verifier only checks for the inits 
and we didn't want to change the verifier here? Given that you can use 
"new ArrayList()" by reflection I don't think that security concerns 
really hold here. They where given for super()... and even though I 
don't understand why (if someone can explain it would be nice) I see a 
"new ArrayList()" security wise as a whole different case than "super()"

Basically it means that even if you wanted to do a Java using 
invokedynamic only, you cannot do. You will at least need an 
invokeSpecial as well. Either only for super() and you do extra method 
name work, or for both.

> P.S.  Value types (see my blog) will need to make <init> be private,
> since the new & invokespecial <init> idiom is totally incompatible with
> value types.  If we bake them into the class file format (which I don't
> advocate at present) we would have to define a syntax for building
> value-type instances that does not mention <init>; this leads to ideas
> like canonical factory methods, of which the obvious name is <new>.  For
> now, I'm just proposing a design pattern (public static factory methods,
> which internally use private new & <init>) that the JVM internally rewrites.

I see that you may want to let the VM create them. But why is new & 
invokespecial totally incompatible? Ignoring the verifier problem, a new 
and invokespecial is still something that could be done kind of 
intrinsic for value types - or not? or do you mean something else?

bye Jochen

-- 
Jochen "blackdrag" Theodorou - Groovy Project Tech Lead
blog: http://blackdragsview.blogspot.com/
german groovy discussion newsgroup: de.comp.lang.misc
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