We will illustrate the concept of classes with an example of rational numbers, that is, numbers of the form q= qN ⁄ qD, where qN and qD are integers.
Figure 8.1: An example of a class declaration
We use rational numbers here only as an example for the class concept. For future work in Python with rational numbers use the fractions module (refer to [6]).
The definition of a class is made by a block command with the class
keyword, the name of the class, and some statements in the block (refer to Figure 8.1):
class RationalNumber: pass
An instance of this class (or in other words, an object of the type RationalNumber
) is created by
r = RationalNumber()
and a query type(a)
returns the answer, <class'__main__.RationalNumber'>
. If we want to investigate whether an object is an instance of this class, we can use this:
if isinstance(a, RationalNumber): print('Indeed it belongs to the class RationalNumber')
So far we've generated an object...