Re: issue with implementing a visitor design pattern

["cl1" <cwlambert76@yahoo.com>]

after having read all the info given here in the newsgroup on this. I
definately open to implementing it with the generics, but
i would like to have it working with the set up i have now. I have written
lots of notes on what i have done so far and getting
it to work in the format i have now would better help me explain why i
changed when i post my writtings to the internet.

here is a link to some example source:
http://www.geocities.com/cwlambert76/preorder_visitor.adb.txt
it contains example code of both packages i have written so far.

what i have so far is a parse tree, along with an Accept_Visitor() operation
for each node. and an abstract
Visitor in my parse_tree_pkg with a Visit() operation for each node. i want
to implement the different types of tree traversal
only once(preorder, inorder, etc.) that is why i have created the
preorder_visitor_pkg. and any visitor that needs to "visit" the
parse tree can pick its traversal method by subclassing the appropriate
visitor package and overiding the Visit_Operation for
each node, and in turn not have to implement the actual traversal itself.
Now i know this may not be the best way to implement
this, at this point the only way to catch that a Visit_Operation() isn't
implemented is at runtime (not good). However this has
been a great learning process for me, and i would like to be able to share
my learning experiances with everyone. So once i
have this working then I will be more than happy to refactor my code to a
higher quality version, and i would greatly
appreciate all of your help in doing so.

Thanks,
Charles Lambert