Core class that implements an object cache.

Sets up object properties; PHP 5 style constructor.

Makes private properties readable for backward compatibility.

Makes private properties checkable for backward compatibility.

Makes private properties settable for backward compatibility.

Makes private properties un-settable for backward compatibility.

Serves as a utility function to determine whether a key exists in the cache.

Adds data to the cache if it doesn’t already exist.

Sets the list of global cache groups.

Adds multiple values to the cache in one call.