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Initially, when n=2, and f(n-2) = 0, and f(n-1) = 1, then f(n) = 0 + 1 = 1. Consider one possible way of modeling production of the Fibonacci sequence.. In the first UML object diagram on the right, the instance in the leftmost instance specification is named v1, has IndependentVariable as its classifier, plays the NMinus2 role within the FibonacciSystem, and has a slot for the val attribute ...
The observer design pattern is a behavioural pattern listed among the 23 well-known "Gang of Four" design patterns that address recurring design challenges in order to design flexible and reusable object-oriented software, yielding objects that are easier to implement, change, test and reuse.
The UML sequence diagram shows the run-time interactions: In this example, the Sender object calls handleRequest() on the receiver1 object (of type Handler). The receiver1 forwards the request to receiver2, which in turn forwards the request to receiver3, which handles (performs) the request.
The visitor object then performs the operation on the element ("visits the element"). This makes it possible to create new operations independently from the classes of an object structure by adding new visitor objects. See also the UML class and sequence diagram below.
In the above UML class diagram, the Director class doesn't create and assemble the ProductA1 and ProductB1 objects directly. Instead, the Director refers to the Builder interface for building (creating and assembling) the parts of a complex object, which makes the Director independent of which concrete classes are instantiated (which ...
A sample UML class and sequence diagram for the Decorator design pattern. [7] In the above UML class diagram, the abstract Decorator class maintains a reference (component) to the decorated object (Component) and forwards all requests to it (component.operation()). This makes Decorator transparent (invisible) to clients of Component.
A sample UML class and sequence diagram for the Memento design pattern. [1]In the above UML class diagram, the Caretaker class refers to the Originator class for saving (createMemento()) and restoring (restore(memento)) originator's internal state.
A sample UML class and sequence diagram for the Command design pattern. [3]In the above UML class diagram, the Invoker class doesn't implement a request directly. Instead, Invoker refers to the Command interface to perform a request (command.execute()), which makes the Invoker independent of how the request is performed.