Re: Java interfaces -> ADA

[stt@houdini.camb.inmet.com (Tucker Taft)]

Emmanuel.Leguy (leguy@lifl.fr) wrote:

: > I guess since an interface says simply that a class that implements it
: > needs to supply those methods, then in Ada, you would have a number
: > of abstract methods for the tag record, and then any one who
: > extends this record, will need to implement those methods since they
: > are abstract.
: > 
: But a java class can inherit more than one interface... The multiple
: inheritance is not permit in ADA.

Ada 95 supports multiple inheritance through a number of building
block mechanisms, including generic "mix-ins" and through the
use of access discriminants.  You are correct that there is no specific
syntax for multiple inheritance, but there are a number of
flexible mechanisms that allow type multi-hierarchies to
be supported.

In our mapping of Ada to/from Java, we use components to implement
Java interfaces.  See http://www.averstar.com/~stt/adajava_paper/
In this case, the compiler helps out by providing a Convention
"Java_Interface."  However, much the same thing can be accomplished
using components each with an access discriminant default initialized
to refer to the enclosing object.  A paper I wrote discussing this approach 
to multiple inheritance is on http://www.adahome.com, I believe.

: --
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--
-Tucker Taft   stt@averstar.com   http://www.averstar.com/~stt/
Technical Director, Distributed IT Solutions  (www.averstar.com/tools)
AverStar (formerly Intermetrics, Inc.)   Burlington, MA  USA