Re: Problem with controlled types

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

Matthew Heaney (matthew_heaney@acm.org) wrote:
: bourguet@my-dejanews.com writes:

: > with ada.finalization;
: > 
: > package Pkg is
: > 
: >    type A is private;
: >    --  operations on B
: > 
: >    type B is private;
: > 
: >    function Get_B (I: A) return B;
: >    -- other operations on B
: > 
: > private
: > 
: >   type A is new Ada.Finalization.Controlled with record
: >      ...
: >   end record;
: > 
: >   type B is new Ada.Finalization.Controlled with record
: >      ...
: >   end record;
: > 
: > end pkg;
: > 
: > ObjectAda complain that the Get_B function is primitive on two tagged
: > types, and that is not allowed.
: > 
: > Gnat compile and run correctly (as A'Class contains only A and
: > B'Class only B, this is not strange).
: > 
: > Now, which one is correct?

: GNAT is correct; ObjectAda is incorrect.

: An operation cannot be primitive for more that one type is only true for
: (publicly) tagged types.  Since A and B and not publically tagged,
: Get_B is a legal operation.

Not quite true.  The problem is that *inside* the package private
part and the body, Get_B is primitive on two tagged types,
and that is not legal.  

So ObjectAda wins this round ;-).

--
-Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
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