12. Communicating Objects

• Object A can access object B if:

  1. A has a relationship with B.

  2. Class of A has a static relationship with B.

  3. A has a relationship with C, and C has a public relationship with B.
     (Also consider static, friendly, and protected variants.)

  4. A obtained a reference to B as an actual parameter to the currently executed method...
     ...for duration of this method only.

  5. A created B,

     • only within the local scope,

     • while holding reference to B.