4Suite API Documentation

Module Ft.Lib.Random

Thread-safe random number generation
Random number generation capabilities, speed, and thread safety in
stdlib vary from version to version of Python. In addition, attempts to
use an OS-specific random number source can result in unexpected
exceptions being raised. Also, a bug in Python 2.3.0 can lead to a
reduction in entropy, and a bug in Python 2.4.0 and 2.4.1 can result
in exceptions related to open filehandles on some multithreaded Posix
platforms.

This module works around as many of these issues as it can by defining
random number generator classes that can be used safely by multiple
threads, using the best random number sources available. They support
all versions of Python from 2.1 up, and fall back on more reliable
generators when exception conditions occur. In addition, convenience
functions equivalent to random.random() and os.urandom() are exposed.

Copyright 2006 Fourthought, Inc. (USA).
Detailed license and copyright information: http://4suite.org/COPYRIGHT
Project home, documentation, distributions: http://4suite.org/
Classes:
Functions:
Globals:

Classes

class FtRandom(random.Random, object)
The best available OS-agnostic PRNG, thread-safe.
Implements getrandbits() in all versions of Python.
Also adds getrandbytes(), which returns a str of bytes.

Methods

__init__(self, *args, **kwargs)
Overrides: __init__ from class Random
gauss = _gauss(self, *args, **kwargs)
Gaussian distribution.
mu is the mean, and sigma is the standard deviation.

Thread-safe.
Overrides: gauss from class Random
getrandbits = _getrandbits(self, k)
getrandbits(k) -> x. Generates a long int with k random bits.
getrandbytes = _getrandbytes(self, k)
getrandbytes(k) -> x. Returns k random bytes as a str.
seed = _best_seed(self, a=None)
Initialize internal state from hashable object.
None or no argument seeds from current time or from an operating
system specific randomness source if available.

If a is not None or an int or long, hash(a) is used instead.
Overrides: seed from class Random

Methods inherited from class random.Random

__getstate__, __reduce__, __setstate__, betavariate, choice, cunifvariate, expovariate, gammavariate, getstate, lognormvariate, normalvariate, paretovariate, randint, randrange, sample, setstate, shuffle, stdgamma, uniform, vonmisesvariate, weibullvariate

Methods inherited from class _random.Random

__getattribute__, __new__, jumpahead, random

Methods inherited from class object

__delattr__, __hash__, __reduce_ex__, __repr__, __setattr__, __str__

Members inherited from class random.Random

VERSION, __dict__, __weakref__

Members inherited from class object

__class__
class FtSystemRandom(FtRandom)
A PRNG that uses an OS-specific random number source, if available, falling back on an instance of FtRandom.
Calls to seed(), jumpahead(), getstate() and setstate() only affect
the fallback FtRandom instance.

Implements getrandbits() in all versions of Python.
Also adds getrandbytes(), which returns a str of bytes.

Methods

__init__(self, *args, **kwargs)
Overrides: __init__ from class FtRandom
getrandbits = _getrandbits(self, *args, **kwargs)
getrandbits(k) -> x. Generates a long int with k random bits.
Overrides: getrandbits from class FtRandom
getrandbytes = _getrandbytes(self, k)
getrandbytes(k) -> x. Returns k random bytes as a str.
Overrides: getrandbytes from class FtRandom
getstate(self)
Return internal state; can be passed to setstate() later.
Overrides: getstate from class FtRandom
jumpahead(self, *args, **kwargs)
Make the fallback PRNG (an instance of FtRandom) jump ahead
Overrides: jumpahead from class FtRandom
random = _random(self)
Get the next random number in the range [0.0, 1.0).
Overrides: random from class FtRandom
seed(self, *args, **kwargs)
Seed the fallback PRNG (an instance of FtRandom)
Overrides: seed from class FtRandom
setstate(self, state)
Restore internal state from object returned by getstate().
Overrides: setstate from class FtRandom

Methods inherited from class FtRandom

Methods inherited from class random.Random

__getstate__, __reduce__, __setstate__, betavariate, choice, cunifvariate, expovariate, gammavariate, lognormvariate, normalvariate, paretovariate, randint, randrange, sample, shuffle, stdgamma, uniform, vonmisesvariate, weibullvariate

Methods inherited from class _random.Random

__getattribute__, __new__

Methods inherited from class object

__delattr__, __hash__, __reduce_ex__, __repr__, __setattr__, __str__

Members inherited from class random.Random

VERSION, __dict__, __weakref__

Members inherited from class object

__class__

Functions

GetRandomBytes(numBytes)
Returns a string of random bytes from the best RNG available. Equivalent to os.urandom(), but failsafe.
Random()
Returns a random float, n, where 0 <= n < 1
urandom(n)
urandom(n) -> str
Return a string of n random bytes suitable for cryptographic use.

Globals

DEFAULT_RNG = <Ft.Lib.Random.FtSystemRandom object>
A PRNG that uses an OS-specific random number source, if available, falling back on an instance of FtRandom.
Calls to seed(), jumpahead(), getstate() and setstate() only affect
the fallback FtRandom instance.

Implements getrandbits() in all versions of Python.
Also adds getrandbytes(), which returns a str of bytes.