Merge branch 'eltoder-feature/numeric-range-calc-len' into issue-732-…

…isqrt

more_itertools/more.py

@@ -2,7 +2,7 @@
 
 from collections import Counter, defaultdict, deque, abc
 from collections.abc import Sequence
-from functools import partial, reduce, wraps
+from functools import cached_property, partial, reduce, wraps
 from heapq import heapify, heapreplace, heappop
 from itertools import (
     chain,
@@ -2075,7 +2075,6 @@ def __init__(self, *args):
         if self._step == self._zero:
             raise ValueError('numeric_range() arg 3 must not be zero')
         self._growing = self._step > self._zero
-        self._init_len()
 
     def __bool__(self):
         if self._growing:
@@ -2151,7 +2150,8 @@ def __iter__(self):
     def __len__(self):
         return self._len
 
-    def _init_len(self):
+    @cached_property
+    def _len(self):
         if self._growing:
             start = self._start
             stop = self._stop
@@ -2162,10 +2162,10 @@ def _init_len(self):
             step = -self._step
         distance = stop - start
         if distance <= self._zero:
-            self._len = 0
+            return 0
         else:  # distance > 0 and step > 0: regular euclidean division
             q, r = divmod(distance, step)
-            self._len = int(q) + int(r != self._zero)
+            return int(q) + int(r != self._zero)
 
     def __reduce__(self):
         return numeric_range, (self._start, self._stop, self._step)