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Template Pattern Tutorial

This tutorial is aimed to guide the definition and application of Gang of Four (GoF) template design pattern. By reading this tutorial, you will know how to develop a model for the template pattern, and how to apply it in practice.

Compatible edition(s): Enterprise, Professional, Standard

  • October 27, 2009
  • Views: 14,363
  • PDF

Modeling Design Pattern with Class Diagram

  1. Create a new project Design Patterns.
  2. Create a class diagram Template.
    new diagram
  3. Select Class from diagram toolbar. Click on the diagram to create a class. Name it as AbstractClass.
    create abstract class
  4. Right click on AbstractClass, and select Model Element Properties > Abstract to set it as abstract.
    set class abstract
  5. Right click on the AbstractClass class, and select Add > Operation from the popup menu.
    add oper to abstract class
  6. Name the operation TemplateMethod().
    template method added
  7. Create another operation PrimitiveOperation1().
    primitive oper added
  8. Right click on PrimitiveOperation1, and select Model Element Properties > Abstract to set it as abstract.
    set primitive oper abstract
  9. Move the mouse cursor over the AbstractClass class, and drag out Generalization > Class to create subclasses ConcreteClass.
    concrete class created
  10. We need to make the concrete classes inherit operations from the abstract class. Right click on ConcreteClass and select Related Elements > Realize all Interfaces from the popup menu.
    realize abstract class
  11. In practice, there may be multiple concrete strategies. To represent this, stereotype the class ConcreteClass, as PTN Cloneable. Right click on ConcreteClass and select Stereotypes > Stereotypes... from the popup menu.
    stereotype concrete class
  12. In the Stereotypes tab of the Class Specification dialog box, select PTN Cloneable and click > to assign it to ConcreteClass class. Click OK to confirm.
    set ptn cloneable
  13. There may be multiple primitive operations. To represent this, stereotype the class AbstractClass as PTN Members Creatable. Repeat steps 11 and 12 to stereotype AbstractClass as PTN Members Creatable.
    stereotype abstract class

Defining Pattern

  1. Select all classes on the class diagram.
    select all classes
  2. Right click on the selection and select Define Design Pattern... from the popup menu.
    define pattern
  3. In the Define Design Pattern dialog box, specify the pattern name Template. Keep the file name as is. Click OK to proceed.
    name pattern

Applying Design Pattern on Class Diagram

In this section, we are going to apply the template pattern in modeling a diagram editor.

  1. Create a new project Diagram Editor.
  2. Create a class diagram Domain Model.
  3. Right click on the class diagram and select Utilities > Apply Design Pattern... from the popup menu.
    apply design pattern
  4. In the Design Pattern dialog box, select Template from the list of patterns.
    select template pattern
  5. At the bottom pane, rename AbstractClass and ConcreteClass to Shape and OvalShape.
    rename classes
  6. We need to have one more concrete class for text shape, click on the + button next to ConcreteClass and select Clone... from the popup menu.
    clone concrete class
  7. Enter 1 to be the number of classes to clone. Click OK to confirm.
    enter clone count
  8. Rename ConcreteClass2 to TextShape.
    rename concrete class2
  9. Rename TemplateMethod and PrimitiveOperation1 to Render and IsTransparent respectively.
    rename opers
  10. Click OK to apply the pattern to diagram.
  11. Tidy up the diagram. Here is the result:
    result



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