#' Constructor EmailClass <- function(name, email) { nc = list( name = name, email = email, get = function(x) nc[[x]], set = function(x, value) nc[[x]] <<- value, props = list(), history = list(), getHistory = function() return(nc$history), getNumMessagesSent = function() return(length(nc$history)) ) #Add a few more functions nc$sendMail = function(to) { cat(paste("Sending mail to", to, 'from', nc$email)) h <- nc$history h[[(length(h)+1)]] <- list(to=to, timestamp=Sys.time()) assign('history', h, envir=nc) } nc$addProp = function(name, value) { p <- nc$props p[[name]] <- value assign('props', p, envir=nc) } nc <- list2env(nc) class(nc) <- "EmailClass" return(nc) } #' Define S3 generic method for the print function. print.EmailClass <- function(x) { if(class(x) != "EmailClass") stop(); cat(paste(x$get("name"), "'s email address is ", x$get("email"), sep='')) } if(FALSE) { #Test code that won't be run when sourcing this file test <- EmailClass(name="Jason", "jason@bryer.org") test$addProp('hello', 'world') test$props test class(test) str(test) test$get("name") test$get("email") test$set("name", "Heather") test$get("name") test test$sendMail("jbryer@excelsior.edu") test$getHistory() test$sendMail("test@domain.edu") test$getNumMessagesSent() test2 <- EmailClass("Nobody", "dontemailme@nowhere.com") test2 test2$props test2$getHistory() test2$sendMail('nobody@exclesior.edu') }