Python Design Patterns - Iterator

Neha Kumawat

9 months ago

The iterator design pattern falls under the behavioral design patterns category. Developers come across the iterator pattern in almost every programming language. This pattern is used in such a way that it helps to access the elements of a collection (class) in a sequential manner without understanding the underlying layer design.

How to implement the iterator pattern?

We will now see how to implement the iterator pattern.

import time

def fib():
   a, b = 0, 1
   while True:
      yield b
      a, b = b, a + b

g = fib()

   for e in g:

except KeyboardInterrupt:
   print("Calculation stopped")


The above program generates the following output −
If you focus on the pattern, the Fibonacci series is printed with the iterator pattern. On forceful termination of user, the following output is printed −


This python code follows the iterator pattern. Here, the increment operators are used to start the count. The count ends on forceful termination by the user.

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