Fields

new_game <- function() {
  # Fields are the elements of the list
  structure(list(name = "", year = 0),
            class = "Game")
}

game <- new_game()
game$name <- "Heroes 3"
game$year <- 1999

# A typo makes a new field, no error
game$yaer <- 2000
# names(game) = name year yaer

cat("game$name =", game$name, "\n")
cat("game$year =", game$year, "\n")
cat("names(game) =", names(game), "\n")