Declaring and using instances of class
An instance is an object whose description is given by the class. The objects
share same methods and attributes, but not same data: each instance may have
proper values for each attributes.
You can declare instances of a class in any scope, including inside other
classes.
Syntax
classename instancename [ = classename( ...arguments...) ]
In order:
- name of the class
- the identifier of the instance
- and if the constructor has arguments:
- the = symbol
- followed by the list or parameter between parenthesis.
Thus:
classname instancename = classname(arguments) ` or
classname instancename
in the second case, the constructor has no argument.
Examples:
Car
mycar = Car(850) Truck mytruck Truck mytruck = Truck(10, 25) |
Using an instance
Once an instance is declared, attributes and methods of the class become
visible outside the class providing they are associated with the name of the
instance by the dot symbol, with this form:
instanceName.attribute
instanceName.method()
Example of instance of the Car class: |
class
Car int speed int power int getSpeed() return speed int getPower() return power void setSpeed(int s) speed = s return /class Car mycar mycar.setSpeed(150) print mycar.speed print mycar.getSpeed() |
Displays: | >
150 > 150 |
Exercises |
1) The class Buggy is defined below... |