The Proxy design pattern provides a solution:
Define a separate Proxy object that acts as substitute for another object (Subject).
Work through a Proxy object to control the access to a real subject.
Describing the Proxy design in more detail is the theme of the following sections.
See Applicability section for all problems Proxy can solve.

• The key idea in this pattern is to work through a separate Proxy object that performs additional functionality when accessing an (already existing) object.
  A proxy implements the Subject interface so that it can act as substitute wherever a subject is expected. Clients do not know whether they are working with a real subject or its proxy.
• Define a separate Proxy object:
  • Define a class (Proxy) that implements arbitrary functionality to control the access to a RealSubject object.
  • "The Proxy pattern introduces a level of indirection when accessing an object. The additional indirection has many uses, depending on the kind of proxy:" [GoF, p210] For example:
    A protection proxy acts as placeholder for sensitive objects
    to check that clients have the required access rights.
    A virtual proxy acts as placeholder for expensive objects
    to defer their creation until they are actually needed.
    A remote proxy acts as placeholder for remote objects
    to hide complex network communication details from clients.