The R6 package also supports inheritance, meaning that we can define a base class (that will act as a parent), and a derived class (that will act as a child). The derived class will be able to access all the methods and attributes defined in the parent class, reducing code duplication, and simplifying its maintainability. In this example, we will create a derived class called Customer_missprod, which will store data for clients who haven't yet received a product they were expecting. Note that the way we achieve this is by using the inherit parameter.

Note that we are overriding the full_print method, and we are printing some extra variables. It is important to understand the difference between the super and self methods—the former is used to refer to attributes or methods present in the base class. We evidently need to override the constructor (already defined in the base class) because we have more variables now:

library(R6)
customers = read.csv("./Customers_data_missing_products.csv")
Customer_missprod = R6Class(inherit = Customer,
                            public=list(Missing_prod = NULL,Missing_since = NULL,
initialize = function(customer_id,name,city,Missing_product,Missing_since){
  super$Customer_id <- customer_id
  super$Name <- name
  super$City <- city
  self$Missing_prod <- Missing_product
  self$Missing_since <- Missing_since
},
full_print = function(){
  print("------------------------------------")
  print(paste("Customer name ->",super$Name))
  print(paste("Customer city ->",super$City))
  print(paste("Missing prod ->",self$Missing_prod))
  print(paste("Missing since ->",self$Missing_since))
  print("------------------------------------")
}
)
)

list_of_customers = list()
for (row in 1:nrow(customers)){
  row_read = customers[row,]
  customer = Customer_missprod$new(row_read$Customer_id,row_read$Name,row_read$City,row_read$Missing_product,row_read$Missing_since)
  list_of_customers[[row]] <- (customer)
}

list_of_customers[[1]]$full_print()

Take a look at the following screenshot: