"""ParamFactory.py

A factory for creating cached, parametrized class instances.

"""

from threading import Lock


class ParamFactory(object):

    def __init__(self, klass, **extraMethods):
        self.lock = Lock()
        self.cache = {}
        self.klass = klass
        for name, func in extraMethods.items():
            setattr(self, name, func)

    def __call__(self, *args):
        self.lock.acquire()
        if args in self.cache:
            self.lock.release()
            return self.cache[args]
        value = self.klass(*args)
        self.cache[args] = value
        self.lock.release()
        return value

    def allInstances(self):
        return self.cache.values()
