Chapter 20 ObjectOriented Concepts and Principles

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Chapter 20Object-Oriented Conceptsand Principles
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The OO Process Model
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The OO Mindset
objects
problem domain
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Key Concepts

• classes and class hierarchies
• instances
• inheritance
• abstraction and hiding
• objects
• attributes
• methods
• encapsulation
• polymorphism
• messages

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Classes

• object-oriented thinking begins with the
  definition of a class often defined as
• template
• generalized description
• pattern
• blueprint ... describing a collection of
  similar items
• a metaclass (also called a superclass) is a
  collection of classes -- hmmmmmmmmm
• once a class of items is defined, a specific
  instance of the class can be defined

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Building a Class
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What is a Class?
occurrences
roles
organizational units
things
places
external entities
structures
class name
attributes
operations
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Encapsulation/Hiding
The object encapsulates both data and the
logical procedures required to manipulate the data
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Class Hierarchy
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Messages