Represents an operation to be performed on the elements of an
object structure. Visitor lets you define a new operation without
changing the classes of the elements on which it operates.
Category:
Behavioral
UML Diagram:
Description of the Demonstration:
In this demonstration a number of instances of Menu are created, each of
which contains any number of MenuItem instances. Each MenuItem can contain
any number of instances of an Ingredient. Each Ingredient is designed so
that it can provide a number of useful bits of information about itself.
When some special information is needed about all items in the Menu collection
an instance of Visitor is created and each Menu is told to "accept" the Visitor.
The Visitor is then able to navigate through all the elements of the Menu
hierarchy structure and gather the needed data then produce the needed
information. New visitors can be created to handle other information
gathering actions. In this demonstration a HealthRatingVisitor was
created after the CalorieCountVisitor and CarbCountVisitor just to
illustrate how new information can be generate without having to
change the structure of the Menus.
Code:
Click here to download a
zip file containing all the source files and an executable of the
Demonstration. See the _ReadMe.txt file in the zip.
