1. OOP features of Jeroo
3-Jul-19

2. Overview In this presentation we will discuss these topics:
OOP terminology
Jeroo syntax
constructors
methods

3. 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.

4. 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

5. 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: Dim Andy as Jeroo = 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
Dim Andy as Jeroo = new Jeroo()
The methods of an object (the actions it can perform)
Example: Andy.hop()
Jeroos can hop, pick flowers, plant flowers, toss nets, and turn.

6. Syntax is important! A class is the type of an object
Each object that is created is named
Dim Andy as Jeroo = new Jeroo(2,5,SOUTH,3);
Andy is an object
Jeroo is the class

7. Sending messages to objects
We don’t 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(WEST);
Susanna.toss(); no extra information needed

8. 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

9. 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)

10. 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

11. The End