17.7. Object Design: makePayment

The makePayment system operation occurs when a cashier enters the amount of cash tendered for payment. Here is the complete contract:

Contract CO4: makePayment

Operation:makePayment( amount: Money )
Cross References:

Use Cases: Process Sale

Preconditions:There is an underway sale.
Postconditions:

- A Payment instance p was created (instance creation).

- p.amountTendered became amount (attribute modification).

- p was associated with the current Sale (association formed).

- The current Sale was associated with the Store (association formed); (to add it to the historical log of completed sales).

A design will be constructed to satisfy the postconditions of makePayment.

Creating the Payment

One of the contract postconditions ...

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