# Die Example
# Create S3 object that simulates rolling
# a single die until a 1 is obtained.

# Constructor
Die <- function( ) {
   this <- list(history=integer(0));
   class(this) <- "Die"
   return(this)
}

# Generic reset method
reset <- function(theObject) {
   UseMethod("reset", theObject)
}

# Default reset method
reset.default <- function(theObject) {
   warning("Default reset method called unrecognized object")
   return(theObject)
}

# Die reset method
reset.Die <- function(theObject) {
   theObject$history <- integer(0)
   return(theObject)
}

# Generic simulation method
simulation <- function(theObject) {
   UseMethod("simulation", theObject)
}

# Default simulation method
simulation.default <- function(theObject) {
   warning("Default simulation method called unrecognized object")
   return(theObject)
}

# Die simulation method
simulation.Die <- function(theObject) {
   theObject <- reset(theObject)
   repeat {
      roll <- as.integer(runif(1, 1, 6.999999999))
      theObject$history <- c(theObject$history, roll)
      if (roll == 1) {
         break
      }
   }
   return(theObject)
}

# Die print method
print.Die <- function(theObject) {
   cat("History: ", theObject$history, "\n")
}

# Die plot method
plot.Die <- function(theObject) {
   this <- theObject
   n <- length(this$history)
   plot(1:n, this$history, main="Roll History",
      xlab="Roll Number", ylab="Roll", ylim=c(1,6),
      type="l")
}

# Create Die object
d <- Die( )

# Repeat these three statements to obtain simulations.
d <- simulation(d)
print(d)
plot(d)