Re: How to properly clean up an extended, generic structure?

["Björn Persson" <spam-away@nowhere.nil>]

Peter C. Chapin wrote:
> I've created a procedure Destroy_Tree that uses an instance of 
> Ada.Unchecked_Deallocation to remove all the nodes in a given tree. 
> Destroy_Tree is meant to be used when a tree is no longer needed and it 
> serves the role of a destructor (using C++ terminology). It occurs to 
> me, though, that Item_Type might have its own clean up needs.

You need controlled types. Derive your tree type from 
Ada.Finalization.Controlled, and instead of Destroy_Tree write a 
procedure Finalize, overriding the Finalize that's declared in 
Ada.Finalization. Finalize will then be executed automatically when the 
object is destroyed.

Item types that need cleaning up should also be controlled. Each item 
will then be finalized when its tree node is finalized.

-- 
Bj�rn Persson                              PGP key A88682FD
                    omb jor ers @sv ge.
                    r o.b n.p son eri nu