Tree structures are interesting. Often the root of the tree is used as a
handle for the tree itself. However, the tree often has additional
methods beyond that of the root node.
I couldn’t figure out how to do this simply via inheritance due to
chicken-and-egg problems with namespacing:
class Tree < Tree::Node
class Node
end
end
#=> chicken-and-egg.rb:1: uninitialized constant Tree (NameError)
I came up with two alternative techniques to achieve the same goal. I’m
not wild about the way either are handled by RDoc (though the first is
substantially better):
Technique 1: Using modules
class Tree
module NodeStuff
#…all the meat here…
end
include NodeStuff
class Node
include NodeStuff
end
end
Technique 2: Conjur the chicken first, and kill it later
class TmpTreeNode
# …all the meat here…
end
class Tree < TmpTreeNode
Node = TmpTreeNode
end
Object.class_eval{ remove_const( :TmpTreeNode ) }
Ideally, IMO, Ruby would let me do this:
No “Tree” module or class has yet been defined;
it is a pure namespace at this point
class Tree::Node
# …all the meat here…
end
Now Tree is a class
class Tree < Tree::Node
end
I don’t have any question, and it’s not important enough to me to make
an RCR for the above. I just thought I’d share these thoughts with the
world.