Managing Attribute Deletion

00:00 Managing Attribute Deletion. It’s possible to create properties that implement deletion functionality. This might be a rare use case of property(), but having a way to delete an attribute can be handy in some situations.

00:17 Let’s say you are implementing your own tree data type. A tree is an abstract data type that stores elements in a hierarchy. The tree components are commonly known as nodes.

00:29 Each node in a tree has a parent node, except for the root node. Nodes can have zero or more children. Now suppose you need to provide a way to delete or clear the list of children of a given node.

00:45 Here’s an example that implements a tree node that uses property() to provide most of its functionality, including the ability to clear the list of children of the node at hand.

00:57 Here, TreeNode represents a node in your custom tree data type. Each node stores its children in a Python list. You then implement .children as a property to manage the underlying list of children.

01:36 The deleter method calls .clear() on the list of children to remove them all.

01:57 Here, you first create a root node to start populating the tree. Then you create two new nodes and assign them to .children using a list.

02:20 The del statement triggers the internal deleter method of .children and clears the list. In the next section of the course, you’ll see how to make class APIs that are backwards-compatible.