Specification of Reactive Hardware/Software Systems - Electronic ...

396 Case Study
data class
PI
instance variables
idNumber : Integer
destination : Destination
requiredServicesSet:
RequiredServicesSet
This part of the class description directly follows from the Object Class Diagram of
Figure 12.9. The instance variable idNumber implements the idNumber attribute. The
aggregation relation of arity ’zero or one’ with the Destination class is implemented
by the destination variable. Finally, the aggregation relation of arity ’zero or more’ is
implemented by a RequiredServicesSet of required services.
Next to the attributes of class PI, the Object Class Diagram of Figure 12.9 also describes
the messages. Since PI is a data class, these messages correspond to the methods in a
one-to-one fashion. The methods are specified as follows:
instance methods
requires(service:Service):Boolean
requiredServicesSet containsMatchOf(service)
markPending(service:Service):PI
requiredServicesSet selectMatchOf(service) markPending;
self
markPerformed(service:Service):PI
requiredServicesSet selectMatchOf(service) markPerformed;
self
Upon invocation of the first (accessor) method, it is evaluated whether the collection requiredServicesSet
contains a RequiredService that matches the value of parameter service 19 .
The result of the evaluation is the result of the method invocation. In the second and the
third (transformer) methods, the RequiredService matching the value of parameter service
is marked ’pending’ respectively marked ’performed’.
The second data class that will be described is Position. The first part of this class is given
by:
data class
Position
instance variables
positionNumber : Integer
19 The actual evaluation is carried out by the instance of class RequiredServicesSet. This class is not further
elaborated.