SF bug 594996: OverflowError in random.randrange
Loosened the acceptable 'start' and 'stop' arguments so that any
Python (bounded) ints can be used. So, e.g., randrange(-sys.maxint-1,
sys.maxint) no longer blows up.
diff --git a/Lib/random.py b/Lib/random.py
index 6debaf3..4d29080 100644
--- a/Lib/random.py
+++ b/Lib/random.py
@@ -75,6 +75,7 @@
from math import log as _log, exp as _exp, pi as _pi, e as _e
from math import sqrt as _sqrt, acos as _acos, cos as _cos, sin as _sin
+from math import floor as _floor
__all__ = ["Random","seed","random","uniform","randint","choice",
"randrange","shuffle","normalvariate","lognormvariate",
@@ -299,7 +300,7 @@
"""
# This code is a bit messy to make it fast for the
- # common case while still doing adequate error checking
+ # common case while still doing adequate error checking.
istart = int(start)
if istart != start:
raise ValueError, "non-integer arg 1 for randrange()"
@@ -307,14 +308,26 @@
if istart > 0:
return int(self.random() * istart)
raise ValueError, "empty range for randrange()"
+
+ # stop argument supplied.
istop = int(stop)
if istop != stop:
raise ValueError, "non-integer stop for randrange()"
+ if step == 1 and istart < istop:
+ try:
+ return istart + int(self.random()*(istop - istart))
+ except OverflowError:
+ # This can happen if istop-istart > sys.maxint + 1, and
+ # multiplying by random() doesn't reduce it to something
+ # <= sys.maxint. We know that the overall result fits
+ # in an int, and can still do it correctly via math.floor().
+ # But that adds another function call, so for speed we
+ # avoided that whenever possible.
+ return int(istart + _floor(self.random()*(istop - istart)))
if step == 1:
- if istart < istop:
- return istart + int(self.random() *
- (istop - istart))
raise ValueError, "empty range for randrange()"
+
+ # Non-unit step argument supplied.
istep = int(step)
if istep != step:
raise ValueError, "non-integer step for randrange()"