Practical Programming, 2nd Edition

Function “Isinstance,” Class Object, and Class Book

Function isinstance reports whether an object is an instance of a class—that is, whether an object has a particular type:

>>> isinstance('abc', str)
True
>>> isinstance(55.2, str)
False

’abc’ is an instance of str, but 55.2 is not.

Python has a class called object. Every other class is based on it:

>>> help(object)
Help on class object in module builtins:

class object
 |  The most base type

Function isinstance reports that both ’abc’ and 55.2 are instances of class object:

>>> isinstance(55.2, object)
True
>>> isinstance('abc', object)
True

Even classes and functions are instances of object:

>>> isinstance(str, ...