Use index() instead of int() to check args of randrange().

Author: serhiy-storchaka

Lib/random.py

@@ -44,6 +44,7 @@
 from _collections_abc import Set as _Set, Sequence as _Sequence
 from itertools import accumulate as _accumulate, repeat as _repeat
 from bisect import bisect as _bisect
+from operator import index as _index
 import os as _os
 
 try:
@@ -208,7 +209,7 @@ def __reduce__(self):
 
 ## -------------------- integer methods  -------------------
 
-    def randrange(self, start, stop=None, step=1, _int=int):
+    def randrange(self, start, stop=None, step=1, _index=_index):
         """Choose a random item from range(start, stop[, step]).
 
         This fixes the problem with randint() which includes the
@@ -218,39 +219,33 @@ def randrange(self, start, stop=None, step=1, _int=int):
 
         # This code is a bit messy to make it fast for the
         # common case while still doing adequate error checking.
-        istart = _int(start)
-        if istart != start:
-            raise ValueError("non-integer arg 1 for randrange()")
+        start = _index(start)
         if stop is None:
-            if istart > 0:
-                return self._randbelow(istart)
+            if start > 0:
+                return self._randbelow(start)
             raise ValueError("empty range for randrange()")
 
         # stop argument supplied.
-        istop = _int(stop)
-        if istop != stop:
-            raise ValueError("non-integer stop for randrange()")
-        width = istop - istart
+        stop = _index(stop)
+        width = stop - start
         if step == 1 and width > 0:
-            return istart + self._randbelow(width)
+            return start + self._randbelow(width)
         if step == 1:
-            raise ValueError("empty range for randrange() (%d, %d, %d)" % (istart, istop, width))
+            raise ValueError("empty range for randrange() (%d, %d, %d)" % (start, stop, width))
 
         # Non-unit step argument supplied.
-        istep = _int(step)
-        if istep != step:
-            raise ValueError("non-integer step for randrange()")
-        if istep > 0:
-            n = (width + istep - 1) // istep
-        elif istep < 0:
-            n = (width + istep + 1) // istep
+        step = _index(step)
+        if step > 0:
+            n = (width + step - 1) // step
+        elif step < 0:
+            n = (width + step + 1) // step
         else:
             raise ValueError("zero step for randrange()")
 
         if n <= 0:
             raise ValueError("empty range for randrange()")
 
-        return istart + istep*self._randbelow(n)
+        return start + step*self._randbelow(n)
 
     def randint(self, a, b):
         """Return random integer in range [a, b], including both end points.

Lib/test/test_random.py

@@ -368,11 +368,14 @@ def test_randrange_errors(self):
         raises(-721)
         raises(0, 100, -12)
         # Non-integer start/stop
-        raises(3.14159)
-        raises(0, 2.71828)
+        self.assertRaises(TypeError, self.gen.randrange, 3.0)
+        self.assertRaises(TypeError, self.gen.randrange, Fraction(3, 1))
+        self.assertRaises(TypeError, self.gen.randrange, 0, 2.0)
+        self.assertRaises(TypeError, self.gen.randrange, 0, Fraction(2, 1))
         # Zero and non-integer step
         raises(0, 42, 0)
-        raises(0, 42, 3.14159)
+        self.assertRaises(TypeError, self.gen.randrange, 0, 42, 3.0)
+        self.assertRaises(TypeError, self.gen.randrange, 0, 42, Fraction(3, 1))
 
     def test_genrandbits(self):
         # Verify ranges