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packagingada

Access child package declarations

Is it possible to access child package declarations from a parent package ?

-- parent.ads
package Parent is
   procedure F(A : Child_Type);
end Parent;

-- parent-child.ads
package Parent.Child is
   type Child_Type is (A, B, C);
end Parent.Child;

The nested version works fine :

-- parent.ads
package Parent is
   package Child is
      type Child_Type is (A, B, C);
   end Child;
   use Child;

   procedure F(A : Child_Type);
end Parent;

And maybe there is another way to do this since I think it is not possible using child packages...

Solution

  • In general, no; the second example works because the specification of Child is known when F is declared in Parent. In light of your previous question on this topic, it may be that you want a clean way to separate multiple implementations of a common specification. This related Q&A discusses two approaches: one using inheritance and the other using a library-based mechanism at compile-time.