[R] help with oop in R - class structure and syntex

tom soyer
Tue, 05 Feb 2008 13:21:52 -0000

Hi,

I read section 5, oop, of the R lang doc, and I am still not sure I
understand how to build a class in R for oop. I thought that since I
understand the oop syntex of Java and VB, I am wondering if the R programmig
experts could help me out by comparing and contrasting the oop syntex in R
with that of Java. For example, the basic class structure in Java is like
this:

public class Bicycle {

    // *the Bicycle class has three fields*
    public int cadence;
    public int gear;
    public int speed;

    // *the Bicycle class has one constructor*
    public Bicycle(int startCadence, int startSpeed, int startGear) {
        gear = startGear;
        cadence = startCadence;
        speed = startSpeed;
    }

    // *the Bicycle class has four methods*
    public void setCadence(int newValue) {
        cadence = newValue;
    }

    public void setGear(int newValue) {
        gear = newValue;
    }

    public void applyBrake(int decrement) {
        speed -= decrement;
    }

    public void speedUp(int increment) {
        speed += increment;
    }

}

Could one of the R experts please illustrate the R class syntex for writing
the R equivalent of the Java Bicycle class above?

Also, in Java, inheritance is done like this:

public class MountainBike extends Bicycle {

    // *the MountainBike subclass has one field*
    public int seatHeight;

    // *the MountainBike subclass has one constructor*
    public MountainBike(int startHeight, int startCadence, int startSpeed,
int startGear) {
        super(startCadence, startSpeed, startGear);
        seatHeight = startHeight;
    }

    // *the MountainBike subclass has one method*
    public void setHeight(int newValue) {
        seatHeight = newValue;
    }

}

What would be the R oop syntex for inheritance in the case of the
MontainBike class?

Thanks!

--
Tom

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