Meta Data and generics

Question

In the development of generics are a big set of opinions how to implement it. In a C++ like language (which gets build into an executable) the most common choice is to do something like macro expansion. In Java on the other hand, it becomes much more complicated to implement generics, not only because Java supports run time loading of classes but it is also a new feature to the language, which makes it more difficult because backward compatibility is needed.
With the ongoing Tiger release, I noticed that generics are somewhat loose. There are many ways to undo what the idea behind generics is. This is mainly because previous build classes need to be able to use modern classes, which can be misinterpret if changing the bytecode semantics.
However, there is the possibility to use Meta Data to setup some of the rules needed by generics. The upside is that generics become much more strict, the downside is that older classes cannot understand it, and the strictness will get lost.
But is this a shame, should it be understood by older classes? Perhaps it is a possibility to provide two different classes. (Or at least, pieces of classes), one which is strict and is secure in the 1.5 environment, and one which is translated from this one, into an older pre-1.5 class, where the security is more loose. It should be possible to override this with injecting the necessary code to prevent malicious use of the class.
Cary on with the good work,
Sjoerd

Answer 1

As a supplement to this, maybe it is possible to use an attribute for this. You could supply compatible to classes which need to be compatible and you could supply strict to classes which need to be strict, such as the following:
// Template only compatible with 1.5 release using meta data
@generic(Generics.STRICT)
class Test<...> {...}
and
// Template compatible with < 1.5 releases, not strict
@generic(Generics.COMPATIBLE)
class Text<...> {...}
I think much more is possible an can be implemented this way, standard the STRICT notation should be implied when using generics.