Operation Specification--Detail Tab

Figure 28 Operation Specification--Detail Tab

Refer to the descriptions in the Introduction to Specifications chapter for information on the specification elements not covered in the following section.

Arguments

This field contains a list of the arguments of the operation. You may express these arguments in your selected implementation language.

The argument list can be rearranged with the click and drag technique. Select an argument from the list, drag it to the location, and release. The list will reflect the new order.

Protocol

This field lists a set of operations that a client can perform on an object and the legal orderings in which they might be invoked. The protocol of an operation has no semantic impact.

Qualifications

This field identifies language-specific features that qualify the method. You will find this especially useful in Common Lisp Object System (CLOS), in which methods can be described as before or after.

Exceptions

This field contains a list of the exceptions that can be raised by the operation. Enter the name of one or more classes identifying the exception.

Size

This field identifies the relative or absolute amount of storage consumed by the invocation of the operation.

Time

This field contains a statement about the relative or absolute time required to complete an operation. Use this field to budget time for the operation.

Concurrency

This field denotes the semantics in the presence of multiple threads of control. The Concurrency field shows the concurrency for the elements of a class. The concurrency of an operation should be consistent with its class.

Table 10 Concurrency Field Options

Type	Description
Sequential (default)	The semantics of the operation are guaranteed only in the presence of a single thread of control. Only one thread of control can be executing in the method at any one time.
Guarded	The semantics of the operation are guaranteed in the presence of multiple threads of control. A guarded class requires collaboration among client threads to achieve mutual exclusion.
Synchronous	The semantics of the operation are guaranteed in the presence of multiple threads of control; mutual exclusion is supplied by the class.

You can set the concurrency of a class only through the Class Specification. The Concurrency field is inactive for class utilities, parameterized class utilities, and instantiated class utilities.

To change the concurrency, click an applicable option in the Concurrency field. You can display the concurrency in the class diagram by clicking Show Concurrency from the shortcut menu.