Object-oriented design for multiple classes

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Chapter 13

• Object-oriented design for multiple classes

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Objectives

• To expand an object-oriented solution to cater
  for multiple classes
• To introduce interface and GUI objects

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13.1

• Object-oriented design for multiple classes

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Object-oriented design for multiple classes

• Advantages in using inheritance
• Saves time because the Parent class contains
  attributes and method that already exist
• Reduce errors because the Parent class method
  have already been tested and used

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13.2

• Interface and GUI objects

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Interface and GUI objects

• Many popular programming languages provide a
  graphical user interface (GUI), which enables the
  programmer to select the elements of the
  programs user interface from a pre-existing
  range of option
• Interface design is a subset of a program design,
  as it concentrates on one aspect of the programs
  performance and implementation

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Interface and GUI objects

• The interface are developed from predesigned
  classes available in the programming language
• The use interface option may include windows,
  buttons, menus, boxes to hold text, drop down
  list and many more

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Summary

• Most object-oriented programs need more than one
  class.
• Classes can be related to each other through
  association, by aggregation or composition or by
  inheritance.
• Polymorphism allows several operations to have
  the same name, but they achieve their purposes by
  different methods.

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Summary

• Using operation overriding, a child class may
  substitute the parent class version of an
  operation with its own specific version.
• With operation overloading, several operations of
  the same name may have different numbers of
  parameters and different algorithms.

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Summary

• Interface design for visual programming languages
  uses object-oriented design principles.
• Interface objects have operations and attributes.
• The choice of interface design can reduce the
  complexity of both an algorithm and the resulting
  program.