I’m building a gui component that has a tree-based data model (e.g. folder structure in the file system). so the gui component basically has a collection of trees, which are just Node objects that have a key, reference to a piece of the gui component (so you can assign values to the Node object and it in turn updates the gui), and a collection of Node children.
one thing I’d like to do is be able to set “styles” that apply to each level of nodes (e.g. all top-level nodes are bold, all level-2 nodes are italic, etc). so I added this to the gui component object. to add nodes, you call AddChild on a Node object. I would like to apply the style here, since upon adding the node I know what level the node is.
problem is, the style info is only in the containing object (the gui object), so the Node doesn’t know about it. I could add a “pointer” within each Node to the gui object, but that seems somehow wrong…or I could hide the Nodes and make the user only be able to add nodes through the gui object, e.g. gui.AddNode(Node new_node, Node parent), which seems inelegant.
is there a nicer design for this that I’m missing, or are the couple of ways I mentioned not really that bad?
It seems to me that the only thing you need is a Level property on the nodes, and use that when rendering a Node through the GUI object.
But it matters whether your Tree elements are Presentation agnostic like XmlNode or GUI oriented like Windows.Forms.TreeNode. The latter has a TreeView property and there is nothing wrong with that.