Trying to access next element using Generator(yield) in a Class

[omm]

Calling __next__ directly is not the best idea.

This line will call the function, which returns a generator.
The generator keeps the state. Then you're calling next on the generator, which yields the first result.

even_nums.filter_even().__next__()

But the generator is afterwards garbage collected because you have no reference to it.

1. even_nums = Even(10, 50, False)
   for num in even_nums.filter_even():
       print(num)
       # only printing

2. results = []
   even_nums = Even(10, 50, False)
   for num in even_nums.filter_even():
       print(num)
       results.append(num)
       # printing and appending to results

3. even_nums = Even(10, 50, False)
   result = list(even_nums.filter_even())

4. even_nums = Even(10, 50, False)
   result = tuple(even_nums.filter_even())

5. even_nums = Even(10, 50, False)
   result = set(even_nums.filter_even())

You can also convert the class into an iterator iterable:

class Even:
    def __init__(self, start, stop):
        self.start = start
        self.stop = stop

    def __iter__(self):
        for i in range(self.start, self.stop + 1):
            if i % 2 == 0:
                yield i


even_numbers = Even(10, 20)
result = list(even_numbers)
print(result)

This is a boring class. So if the only functionality is to filter out even numbers, you can turn it into a function/generator.

def filter_even_numbers(sequence):
        for number in sequence:
            if number % 2 == 0:
                yield number


numbers = [1,2,3,4,5,6]
result = list(filter_even_numbers(numbers))

If you need to select a start and stop index of your sequence, you can do it with the subscription:

numbers = [1,2,3,4,5,6]
numbers_to_process = numbers[1:]
# from index 1 to ...

result = list(filter_even_numbers(numbers_to_process))

Thanks for your patience and explaining it very clearly.