# No constructor: a list tagged with a class
nokia_phone <- structure(list(model = ""),
class = "Phone")
nokia_phone$model <- "Nokia 6610"
iphone18 <- structure(list(model = ""),
class = "Phone")
iphone18$model <- "iPhone 18"
# No phone yet
kim <- structure(list(first_name = "",
last_name = "",
personal_phone = NULL),
class = "Employee")
# Not assigned yet
no_phone <- is.null(kim$personal_phone)
# no_phone = TRUE
kim$first_name <- "Victoria"
kim$last_name <- "Kim"
kim$personal_phone <- iphone18
cat("no_phone =", no_phone, "\n")
cat("kim$personal_phone$model =",
kim$personal_phone$model, "\n")
cat("nokia_phone$model =",
nokia_phone$model, "\n")
cat("class(kim) =", class(kim), "\n")