+
−"Base Cache class."
+
−
+
−from django.core.exceptions import ImproperlyConfigured
+
−
+
−class InvalidCacheBackendError(ImproperlyConfigured):
+
−    pass
+
−
+
−class BaseCache(object):
+
−    def __init__(self, params):
+
−        timeout = params.get('timeout', 300)
+
−        try:
+
−            timeout = int(timeout)
+
−        except (ValueError, TypeError):
+
−            timeout = 300
+
−        self.default_timeout = timeout
+
−
+
−    def add(self, key, value, timeout=None):
+
−        """
+
−        Set a value in the cache if the key does not already exist. If
+
−        timeout is given, that timeout will be used for the key; otherwise
+
−        the default cache timeout will be used.
+
−
+
−        Returns True if the value was stored, False otherwise.
+
−        """
+
−        raise NotImplementedError
+
−
+
−    def get(self, key, default=None):
+
−        """
+
−        Fetch a given key from the cache. If the key does not exist, return
+
−        default, which itself defaults to None.
+
−        """
+
−        raise NotImplementedError
+
−
+
−    def set(self, key, value, timeout=None):
+
−        """
+
−        Set a value in the cache. If timeout is given, that timeout will be
+
−        used for the key; otherwise the default cache timeout will be used.
+
−        """
+
−        raise NotImplementedError
+
−
+
−    def delete(self, key):
+
−        """
+
−        Delete a key from the cache, failing silently.
+
−        """
+
−        raise NotImplementedError
+
−
+
−    def get_many(self, keys):
+
−        """
+
−        Fetch a bunch of keys from the cache. For certain backends (memcached,
+
−        pgsql) this can be *much* faster when fetching multiple values.
+
−
+
−        Returns a dict mapping each key in keys to its value. If the given
+
−        key is missing, it will be missing from the response dict.
+
−        """
+
−        d = {}
+
−        for k in keys:
+
−            val = self.get(k)
+
−            if val is not None:
+
−                d[k] = val
+
−        return d
+
−
+
−    def has_key(self, key):
+
−        """
+
−        Returns True if the key is in the cache and has not expired.
+
−        """
+
−        return self.get(key) is not None
+
−
+
−    def __contains__(self, key):
+
−        """
+
−        Returns True if the key is in the cache and has not expired.
+
−        """
+
−        # This is a separate method, rather than just a copy of has_key(),
+
−        # so that it always has the same functionality as has_key(), even
+
−        # if a subclass overrides it.
+
−        return self.has_key(key)