OOP features of Jeroo

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OOP features of Jeroo
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Overview

• In this presentation we will discuss these
  topics
• OOP terminology
• Jeroo syntax
• constructors
• methods

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OOP syntax

• Object oriented programming defines objects
• Each Jeroo you create is an object.
• an object has properties
• For example
• a Jeroo has a location
• number of flowers in its pouch
• a direction it is facing
• an object has methods (things it can do)
• a Jeroo can hop, pick, plant and toss.

these properties must be set to an initial value
when the Jeroo is created, and change as the
Jeroo acts.
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Classes definitions of objects

• When you create a new object it is constructed.
• An object may be constructed a number of
  different ways.

this is the default constructor
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Classes

• A class describes 3 things
• What kind of data is in an object
• Example a Jeroo object contains three types of
  information
• its location,
• its direction,
• and the number of flowers in its pouch.
• How to make a new object of that class
• Example Jeroo andy new Jeroo(2,5,SOUTH,3)
• Location row 2, column 5
• Direction SOUTH
• Holding 3 flowers
• The default constructor creates a Jeroo at
  location 0,0 facing EAST with no flowers
• Jeroo andy new Jeroo()
• The methods of an object (the actions it can
  perform)
• Example andy.hop()
• Jeroos can hop, pick flowers, plant flowers,
  toss flowers into nets, give flower to another
  Jeroo, and turn.

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Syntax is important!

• A class is the type of an object
• Each object that is created is named
• Jeroo andy new Jeroo(2,5,SOUTH,3)
• andy is an object
• Jeroo is the class

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Sending messages to objects

• We dont perform operations on objects, we talk
  to them
• This is called sending a message to the object
• A message looks like this
• object.method(extra information)
• The object is the thing we are talking to
• The method is a name of the action we want the
  object to take
• The extra information is anything required by the
  method in order to do its job (also called a
  parameter)
• Examples
• andy.turn(RIGHT)
• susanna.toss() no extra
  information needed

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Messages and methods

• Messages can be used to
• Give an object some information
• Tell an object to do something
• Ask an object for information (usually about
  itself)
• Any and all combinations of the above
• A method is something inside the object that
  responds to your messages
• A message contains commands to do something

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Using OOP syntax

• Rewrite the following English statements as
  object oriented messages
• Tell the woman named clarissa to walk 2 steps
• clarissa.walk(2)
• Tell the Jeroo named alan to turn to the right
• alan.turn(RIGHT)

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Vocabulary Review

• class the type, or description, of an object
• Jeroo classes are descriptions of
• island, water, flower, net, jeroo
• constructor a way to create an object. comes as
  part of the class definition.
• object an instance, or member, of a class
• You can only create Jeroos in your code, all
  other objects must be created visually.
• message something that you say to an object,
  either telling it something or asking it for
  information
• parameter information sent to a method

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The End