Polymorphism question

[Robert Oeckl <oeckl@pheno.physics.wisc.edu>]

I have problems to figure out, how Polymorphism works in Ada. I want to
know if and how the following is possible in Ada:

Suppose I have an abstact type A. Now I have two (non-abstract)
descendants B and C of A. Furthermore there is a descendant D of C. For
A an abstract procedure P1 is defined and for B and C P1 is overloaded.
I do also want to be able to call P1 with type D without explicitly
defining P1 for D, so that the procedure as defined for type C is
executed with type D.
Now I have a procedure P2 defined for type C. For type D I want to
overload this procedure. But in the overloaded procedure I want make a
call to P2 as defined for C, if possible without loosing the information
that the object is actually of type D inside the called procedure.

I hope my description of the problem is clear enough. I would greatly
appreciate any code-examples.

Thanks in advance,

Robert


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Robert Oeckl, graduate student
University of Wisconsin
Department of Physics
1150 University Avenue
Madison WI 53706-1390, USA

phone: +1 (608) 262-8947
e-mail: oeckl@pheno.physics.wisc.edu