RE: The problem of History Objects

["Jing Xue" <jxue01@cs.fiu.edu>]

I would use the following design:


 __________                ____________________        _______________
 |        |          1...1 |HomeAddressManager|   1...*|             |
 | Person |--------------- |                  |--------|HomeAddress  |
 |        |                |                  |        |             |
 ----------                --------------------        ---------------
                                                               |
                                                               |
                                                               |1...1
                                                         ______________
                                                         |            |
                                                         | TimePeriod |
                                                         |            |
                                                         --------------

It is HomeAddressManager's responsibility to define, and maintain the
relationship between Person and HomeAddress.  To do that, HomeAddressManager
provides the following services:

      HomeAddress getFirstValidAddress();
      HomeAddress getNextValidAddress();

This couple of services allows the client to retrieve all available valid
addresses of a Person.  In you case, you might want to make a class deriving
from HomeAddressManager, named, say, HomeAddressManager1, to implement the
constraint that one Person can have only one current address.
HomeAddressManager1 provides a service called
      HomeAddress getCurrentAddress();
And overloads getFirstValidAddress() to use the return value
getCurrentAddress(), and getNextValidAddress() to simply return null.

Jing
-----
Jing Xue
* Let's work the problem, people! Let's not make things worse by guessing.
*                                              -- Gene Kranz, "Apollo 13"

>
> __________                __________________         _______________
> |        |          1...* |HomeAddressTimer |   1...1|             |
> | Person |--------------- |                 |--------|HomeAddress  |
> |        |                |                 |        |             |
> ----------                ------------------|        ---------------
>                             |               |
>                             |               |
>                             |1...1          |1...1
>                         ______________    _____________
>                         |            |    |           |
>                         | TimePeriod |    |    Valid  |
>                         |            |    |           |
>                         --------------    -------------
>

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