13.4. Postconditions

Notice that each of the postconditions in the enterItem example included a categorization such as instance creation or association formed. Here is a key point:

The postconditions describe changes in the state of objects in the Domain Model. Domain Model state changes include instances created, associations formed or broken, and attributes changed.

Postconditions are not actions to be performed during the operation; rather, they are declarations about the Domain Model objects that are true when the operation has finished—after the smoke has cleared.

To summarize, the postconditions fall into these categories:

  • Instance creation and deletion.

  • Attribute modification.

  • Associations (to be precise, UML links) formed and broken. ...

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