Proxy Pattern

The Proxy Pattern puts a stand-in with the same interface in front of an object, to control access to it, or when it is created, or what it costs.

Sometimes the real object should not be used directly, or not yet:

• It is expensive to build, and most runs never need it. Loading a hundred megabyte report at start-up wastes time in the nine runs out of ten that never open it.
• Not every caller is allowed to use it, and the permission check does not belong inside the object.
• It lives on another machine, and callers should not have to write network code.