Checkpoint iterators

checkpoint.py

class CheckpointIter:
    def __init__(self):
        self.checkpoints = list()
        
    def every(self, n_items, do_this):
        self.checkpoints.append((n_items, do_this))
    
    def iter(self, iterable):
        i = 1
        for item in iterable:
            yield item
            for n, do_this in self.checkpoints:
                if i % n == 0:
                    do_this(i)
            i += 1

ci = CheckpointIter()
ci.every(10, lambda i: print("every 10: {}".format(i)))
ci.every(24, lambda i: print("every 24: {}".format(i)))
sum = 0
for x in ci.iter(range(100)):
    sum += x
print("sum is {:,}".format(sum))

# every 10: 10
# every 10: 20
# every 24: 24
# every 10: 30
# every 10: 40
# every 24: 48
# every 10: 50
# every 10: 60
# every 10: 70
# every 24: 72
# every 10: 80
# every 10: 90
# every 24: 96
# every 10: 100
# sum is 4,950

cutesy_checkpoint.py

class _Every:
    def __init__(self, parent, n_items):
        self.parent = parent
        self.n_items = n_items

    def do(self, fn):
        self.parent._add_checkpoint(self.n_items, fn)
            
class CutesyCheckpointIter:

                    
    def __init__(self):
        self.checkpoints = list()
    
    def _add_checkpoint(self, n_items, do_this):
        self.checkpoints.append((n_items, do_this))

    def every(self, n_items):
        return _Every(self, n_items)
    
    def __call__(self, iterable):
        i = 1
        for item in iterable:
            yield item
            for n, do_this in self.checkpoints:
                if i % n == 0:
                    do_this(i)
            i += 1

cute = CutesyCheckpointIter()
cute.every(10).do(lambda i: print("cute 10: {}".format(i)))
cute.every(24).do(lambda i: print("cute 24: {}".format(i)))
sum = 0
for x in cute(range(100)):
    sum += x
print("sum is {:,}".format(sum))

# cute 10: 10
# cute 10: 20
# cute 24: 24
# cute 10: 30
# cute 10: 40
# cute 24: 48
# cute 10: 50
# cute 10: 60
# cute 10: 70
# cute 24: 72
# cute 10: 80
# cute 10: 90
# cute 24: 96
# cute 10: 100
# sum is 4,950