Chapter 13 – Class and Type
--------------------------------

Overview
--------
This chapter explores Python’s approach to *type* and how it relates to classes
and instances. It clarifies what “type” means in Python and how strong vs.
dynamic typing is realized. :contentReference[oaicite:3]{index=3}

Three Types of Type
-------------------
There are multiple notions of type in programming:

- The runtime type of an object (`type(obj)`)
- The static annotated type (type hints)
- Conceptual type based on behavior

Primitive Data Types
--------------------
Built‑in types like `int`, `str`, and `float` have fixed behaviors but are still
Python objects.

Class‑Based Type
----------------
Every class defines a type. When you create a class, you create a new type.

Hierarchical Typing
------------------
Python’s inheritance hierarchy means types can participate in subclass
relationships. For example:

.. code-block:: python

    isinstance(obj, Base)

Instance and Subclass
---------------------
`isinstance` and `issubclass` help test whether an object belongs to a type or
whether a class is derived from another.

Duck Typing
-----------
Python generally uses *duck typing* — if an object has the right methods and
attributes, its type often doesn’t matter for correctness:

.. code-block:: python

    def quack(duck):
        duck.quack()

As long as `duck` has a `quack` method, this works irrespective of actual type.

Summary
-------
Python’s notion of type combines runtime objects, class definitions, and
behavioral expectations rather than rigid compile‑time constraints.