Question

I am making a windows forms application. I am using a TreeView to display the Namespaces.

        var namespaces = assembly.GetTypes()
            .ToLookup(ns => ns.Namespace);


        foreach (var subNamespace in namespaces)
        {
            TreeNode assemblyNode = multiSelectMethodTree.Nodes
                                             .Add(subNamespace.Key);                
        }

Since there is a huge number of Methods and Classes in the project, I thought of displaying the classes only when the user clicks to expand(‘+’) a namespace, and display methods when a class is expanded.

    private void MultiSelectMethodTree_AfterExpand(object sender, TreeViewEventArgs e)
    {
        TreeNode expandedNode = e.Node;
    }

In the AfterExpand event, I am not able to identify whether it is a namespace or a class.

Answer 1

You could inherit from TreeNode class to create specific types each for Namespace, Class, Enum etc.

Example:

public class NamespaceTreeNode : TreeNode { /* May add suited properties. */ }

And instead of creating TreeNode object, create an object of these types.

To identify which node is selected, you can do following:

private void MultiSelectMethodTree_AfterExpand(object sender, TreeViewEventArgs e)
{
    TreeNode expandedNode = e.Node;

    if(expandedNode is NamespaceTreeNode) { /* TODO */ }
}