SafeVarargs classfile encoding (original) (raw)

Rémi Forax forax at univ-mlv.fr
Fri Jan 21 11:53:16 PST 2011

On 01/21/2011 08:34 PM, Joe Darcy wrote:

Rémi Forax wrote:

On 01/21/2011 07:50 PM, Joe Darcy wrote:

Hi Rémi.

A few comments, in the entirety of the "jdk" repository, there were a total of five methods where it was appropriate to add this annotation, which is not a very high density! For Coin, to keep the features small, we're avoiding JVM changes and defining a new attribute is a JVM changes of sorts. Here is the JVM spec change: [snip] The size of the JVM change is not the problem; the fact that potentially all class file consuming tools would need to know about the attribute is.

No because it's an empty attribute. I will be ignored by classfile reader, and copied by classfile read/writer. see section 4.7.1 of the VM spec.

Additionally, this would be a new kind of side-effect of annotating a method.

I don't understand your point here. SafeVarargs doesn't alter the semantics of a method for the VM, like Deprecated or Synthetic which are already defined as attribute.

Using an annotation to store this information avoids the need to add a new core reflection API to access it, Method.isSafeVarargs, etc. Why SafeVarargs need to be visible using reflection API ? Why should the information be excluded? This annotation is a statement about the semantics of the method.

This annotation doesn't alter the runtime semantics of a method.

By example, Synthetic attribute is not visible using reflection API.

Some synthetic information is exposed in core reflection: http://download.java.net/jdk7/docs/api/java/lang/Class.html#isSynthetic() http://download.java.net/jdk7/docs/api/java/lang/reflect/Constructor.html#isSynthetic() http://download.java.net/jdk7/docs/api/java/lang/reflect/Method.html#isSynthetic() http://download.java.net/jdk7/docs/api/java/lang/reflect/Field.html#isSynthetic()

Ok, bad example.

-Joe

Rémi

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