С параметрами по умолчанию

Классы / Конструкторы

new_man <- function(name = "unknown",
                    country = "unknown") {
  structure(list(name = name,
                 country = country),
            class = "Man")
}

man1 <- new_man()
# man1$name = unknown
# man1$country = unknown

man2 <- new_man("Vladimir")
# man2$name = Vladimir
# man2$country = unknown

man3 <- new_man(country = "Brazil")
# man3$name = unknown
# man3$country = Brazil

man4 <- new_man("Vladimir", "Brazil")
# man4$name = Vladimir
# man4$country = Brazil

cat("man1$name =", man1$name, "\n")
cat("man1$country =", man1$country, "\n")
cat("man2$name =", man2$name, "\n")
cat("man2$country =", man2$country, "\n")
cat("man3$name =", man3$name, "\n")
cat("man3$country =", man3$country, "\n")
cat("man4$name =", man4$name, "\n")
cat("man4$country =", man4$country, "\n")