Store Objects on Disk Automatically
Description
Automatically stores objects in files on disk
so that files are rewritten when objects are changed, and
so that objects are accessible but do not occupy memory
until they are accessed. Keeps track of times when objects
are created and modified, and caches some basic
characteristics of objects to allow for fast summaries of
objects. Also provides a command history mechanism that
saves the last command to a history file after each
command completes.