experiment.py

import random

class DontExperiment(Exception):
    pass

def experiment(rate=0.1):
    """ 
    Generate an experiment decatorator; it will raise an DontExperiment
    exception with a probability of <rate>.
    
    >>> @experiment(rate=0.5)
    >>> def prototype(foo, bar):
    >>>    return foo*bar
    >>>
    >>> try:
    >>>     res = prototype(10, 10)
    >>> except DontExperiment:
    >>>     res = 10+10
    """
    def decorator(exp):
        def ret(*args, **kwargs):
            if rate > random.random():
                raise DontExperiment(exp.__name__)
            return exp(*args, **kwargs)
        return ret 
    return decorator