Raise KeyError if no value present and no

        createfunc specified.

        """

        cache, cache_key = _get_cache_parameters(self)

        ret = cache.get_value(cache_key, createfunc=createfunc)

        if merge:

            ret = self.merge_result(ret, load=False)

        return ret

    def set_value(self, value):

        """Set the value in the cache for this query."""

        cache, cache_key = _get_cache_parameters(self)

        cache.put(cache_key, value)        

def query_callable(manager):

    def query(*arg, **kw):

        return CachingQuery(manager, *arg, **kw)

    return query

def get_cache_region(name, region):

        if region not in beaker.cache.cache_regions:

        kw = beaker.cache.cache_regions[region]

        return beaker.cache.Cache._get_cache(name, kw)

def _get_cache_parameters(query):

    """For a query with cache_region and cache_namespace configured,

    return the correspoinding Cache instance and cache key, based

    on this query's current criterion and parameter values.

    """

    if not hasattr(query, '_cache_parameters'):

        raise ValueError("This Query does not have caching parameters configured.")

    region, namespace, cache_key = query._cache_parameters

    namespace = _namespace_from_query(namespace, query)

    if cache_key is None:

        # cache key - the value arguments from this query's parameters.

        args = _params_from_query(query)

        cache_key = " ".join([str(x) for x in args])

    # get cache

    #cache = query.cache_manager.get_cache_region(namespace, region)

    cache = get_cache_region(namespace, region)