Many of the examples we've looked at have either been scalar functions, or relatively simple structures built from small tuples. We can often exploit Python's immutable namedtuple as a way to build complex data structures. We'll look at how we use and how we create namedtuples. We'll also look at ways that immutable namedtuples can be used instead of stateful object classes.

One of the beneficial features of object-oriented programming is the ability to create complex data structures incrementally. In some respects, an object is simply a cache for results of functions; this will often fit well with functional design patterns. In other cases, the object paradigm provides for property methods that include sophisticated calculations. This is an even better fit for functional design ideas.

In some cases, however, object class definitions are used statefully to create complex objects. We'll look at a number of alternatives that provide similar features without...