how to do random / SystemRandom switch

[Peter Otten]

Matthias Kievernagel wrote:

> In my top-level script I want to select if my program
> is to use random.xxx functions or the random.SystemRandom.xxx
> ones. All the other modules shouldn't know about that
> switch and simply use
> import random
> ...
> return random.randint(1, 6)
> ...
> for example.

You can inject the SystemRandom instance into the sys.modules cache:

>>> import random
>>> random
<module 'random' from '/usr/lib/python2.6/random.pyc'>
>>> sr = random.SystemRandom()
>>> import sys
>>> sys.modules["random"] = sr

Then use it in the other modules:

>>> import random
>>> random
<random.SystemRandom object at 0x1acdb60>

Another approach is to monkey-patch the random module:

import random
sr = random.SystemRandom()
random.randrange = sr.randrange
random.randint = sr.randint
...