Re: variant records

[stuart@inmet.UUCP]

Objects created with an allocator are always constrained.  If 
explicit constraints are not supplied, the object is constrained 
by the default discriminant values (LRM 4.8(5)).  The easiest 
solution would be to declare the type "node" without discriminants:

    type node;
    type node_ptr is access node;
    type node is
        record
            next : node_ptr;
            xrec : rec;      -- will not be constrained
        end record;

If you want save space by allocating exact sized constrained objects,
"node" can be declared with discriminates.  However, calls on "new"
must include a constraint, and the free list would have to be an array 
of free lists, one for each possible discriminant value.