Martin Carlisle wrote:
>It should be noted that Ada 95 also supports "multiple views" (see Section
>4.6.3 of the Ada 95 Rationale).  Admittedly the syntax is more complex than
>Java interfaces, and dynamic testing of interfaces (does object X support
>interface Y?) is not allowed; however, it would seem adequate for their
>purposes given the limited information at the URL you mentioned.

They refer to this technique at some point in their analysis, saying that
it's theoretically possible to use Ada in the context of their framework, but
that the technique introduces too much complexity into the code, and too many
extra classes.  This latter is presumably because a view has to specify some
type for the access discriminant, so if the "outer" types are unrelated to
each other, multiple view types would have to be declared.

- Ed