SUNY Geneseo Department of Computer Science

Object Oriented Programming Concepts

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Misc

Problems with CodeWarrior and robot?

Questions?

"Gateway labs" = self-paced, on-line, reviews that will exist but don't yet -- ignore references to them in book

Reading Summary

Chapter 2 through Section 2.6

Object oriented programming

Objects, e.g., robots. Instance of class

• "Instance" = member of class, example of class
• Identifiable behaviors

Methods = how object does what it does, set of instructions object follows to do something

• Message = signal that tells object to do something
  • Message invokes method
• Some messages/methods have side-effects, some produce result
  • Difference = side-effect is change to environment
    • vs returning a value to client

Classes = e.g., all robots, so object is part of class

• Class = set of objects (or possible objects)

Preconditions = variables set before program, e.g., size of room, constraints on parameters

Postconditions = results from program

• Client vs implementor
• Client = customer, puts forth preconditions
• Implementor responsible for postconditions

Abstraction: client and implementor don't need lots of details about each other

• Abstraction = hiding details in order to emphasize a few important features

Subclasses = subsets of a class

• Distinguished by additional or different behaviors

Expressions = e.g., x * y, concatenation of strings

Values = what you can get from expressions

Next

Expand a little on the last items from the reading summary, look at some concrete examples of algorithms that use objects.

No reading or mini-assignment

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