diff options
| -rw-r--r-- | Lib/random.py | 5 | ||||
| -rw-r--r-- | Lib/test/test_random.py | 19 | ||||
| -rw-r--r-- | Misc/NEWS | 7 |
3 files changed, 30 insertions, 1 deletions
diff --git a/Lib/random.py b/Lib/random.py index f502d1d..fe25642 100644 --- a/Lib/random.py +++ b/Lib/random.py @@ -116,7 +116,6 @@ class Random: """ self.seed(x) - self.gauss_next = None ## -------------------- core generator ------------------- @@ -150,6 +149,8 @@ class Random: a, z = divmod(a, 30322) self._seed = int(x)+1, int(y)+1, int(z)+1 + self.gauss_next = None + def random(self): """Get the next random number in the range [0.0, 1.0).""" @@ -238,6 +239,8 @@ class Random: # Zero is a poor seed, so substitute 1 self._seed = (x or 1, y or 1, z or 1) + self.gauss_next = None + def whseed(self, a=None): """Seed from hashable object's hash code. diff --git a/Lib/test/test_random.py b/Lib/test/test_random.py new file mode 100644 index 0000000..d508c9f --- /dev/null +++ b/Lib/test/test_random.py @@ -0,0 +1,19 @@ +import test_support +import random + +# Ensure that the seed() method initializes all the hidden state. In +# particular, through 2.2.1 it failed to reset a piece of state used by +# (and only by) the .gauss() method. + +for seed in 1, 12, 123, 1234, 12345, 123456, 654321: + for seeder in random.seed, random.whseed: + seeder(seed) + x1 = random.random() + y1 = random.gauss(0, 1) + + seeder(seed) + x2 = random.random() + y2 = random.gauss(0, 1) + + test_support.vereq(x1, x2) + test_support.vereq(y1, y2) @@ -104,6 +104,13 @@ Extension modules Library +- random.gauss() uses a piece of hidden state used by nothing else, + and the .seed() and .whseed() methods failed to reset it. In other + words, setting the seed didn't completely determine the sequence of + results produced by random.gauss(). It does now. Programs repeatedly + mixing calls to a seed method with calls to gauss() may see different + results now. + - The pickle.Pickler class grew a clear_memo() method to mimic that provided by cPickle.Pickler. |