item <- function(name, sell_in, quality) { newItem <- list(name=name, sell_in=sell_in, quality=quality) class(newItem) <- 'item' newItem } as.character.item <- function(item) { paste(item$name, ", ", item$sell_in, ", ", item$quality, sep='') } print.item <- function(item) { print.default(as.character(item)) }