Question

In python : Create an iterator design pattern whose instance would iterate over a generator. Here, the generator function should display infinite multiples of 7. an iterator object that will use the pattern will display the 10 values of the multiples of 7 starting from 105.(using yield and next function)

Answer 1

Here is the completed code for this problem. Comments are included, go through it, learn how things work and let me know if you have any doubts or if you need anything to change. If you are satisfied with the solution, please rate the answer. If not, PLEASE let me know before you rate, I’ll help you fix whatever issues. Thanks

Note: Please maintain proper code spacing (indentation), just copy the code part and paste it in your compiler/IDE directly, no modifications required.

#code

#an iterator class that iterates through a generator
class CustomIterator:
    #constructor taking a generator as parameter
    def __init__(self, generator):
        #assigning generator to instance variable
        self.__gen=generator

    def __iter__(self):
        #returns the iterator
        return self

    #returns the next element from generator if exists
    def __next__(self):
        #inside try-except block, calling and returning next() in gen object
        try:
            next_val=next(self.__gen)
            return next_val
        except:
            #in case of any exception, raising StopIteration flag
            raise StopIteration
#end of iterator class


#a generator function that returns infinite multiples of 7 starting with
#a given value (if provided, else uses 7 as start value)
def multiple_7_gen(start_value=7):
    #if start_value is not a multiple of 7, looping and incrementing start_value
    #continuously until start_value is a multiple of 7
    while start_value%7!=0:
        start_value+=1
    #now looping forever
    while True:
        #yielding start_value
        yield start_value
        #incrementing start_value by 7 for the next value
        start_value+=7
#end of multiple_7_gen method

#creating a CustomIterator object, passing a multiple_7_gen generator with start value=105
it=CustomIterator(multiple_7_gen(105))
#looping and printing first 10 multiples of 7 starting with 105
for i in range(10):
    print(next(it))

#output

105
112
119
126
133
140
147
154
161
168