"""Clean Code in Python - Chapter 7: Using Generators
> Idiomatic Iteration with itertools
"""
import logging
from itertools import filterfalse, tee
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)
class IteratorWrapper:
def __init__(self, iterable):
self.iterable = iter(iterable)
def __next__(self):
value = next(self.iterable)
logger.debug(
"%s Producing next value: %r", self.__class__.__name__, value
)
return value
def __iter__(self):
return self
def partition(condition, iterable):
"""Return 2 new iterables
true_cond, false_cond = partition(condition, iterable)
* in true_cond, condition is true over all elements of iterable
* in false_cond, condition is false over all elements of iterable
"""
for_true, for_false = tee(iterable)
return filter(condition, for_true), filterfalse(condition, for_false)
iterable = IteratorWrapper(
{"name": f"element_{i}", "index": i} for i in range(20)
)
def is_even(record):
return record["index"] % 2 == 0
def show(records):
return ", ".join(e["name"] for e in records)
if __name__ == "__main__":
even, odd = partition(is_even, iterable)
logger.info(
"\n\tEven records: %s\n\t Odd records: %s", show(even), show(odd)
)
