OO implementation in Ada

[oconnor@apci.net (James O'Connor)]

All,
	I was discussing some OO concepts and their implementation in various 
languages with a friend and a question came up.  I have a class and 
a function that takes as a parameter an object of that class.  We
 were talking about implmenting it in various languages (Ada, Smalltalk, Java, C++).
  In most of the above languages I can subclass from the original class and send 
 objects of the subclass to the function in the same manner as objects of the parent.
  Is that true with Ada95?  Can I use objects of the subclass of a class any place 
that I can use objects of the parent class (especially, can/are clients unconcerned 
with the difference?).  I'm also curious if operations in the parent class that are 
overridden in the child class get call properly from clients that are only aware of the
 parent class.

I hope this makes sense.  I'm trying to describe an OO modelling situation that I 
would like to mirror in Ada95 specifically without providing any leading information
 on what I expect that implementation to look like because I don't know enough to
 speculate (Does it involve access types?  tagged types? 'Class tags or something else?)

Thanks

James O'Connor
oconnor@apci.net