Cloning R6 Objects

Object-Oriented Programming with S3 and R6 in R

Richie Cotton

Data Evangelist at DataCamp

Environments use copy by reference
So do R6 objects

thing_factory <- R6Class(
  "Thing",

  private = list(
    ..a_field = 123
  ),

  active = list(
    a_field = function(value) {
      if(missing(value)) {
        private$..a_field
      } else {
        private$..a_field <- value
      }
    }
  )

)

a_thing <- thing_factory$new()
a_copy <- a_thing

a_thing$a_field <- 456

a_copy$a_field

`clone()` copies by value

a_clone <- a_thing$clone()

a_thing$a_field <- 789
a_clone$a_field

container_factory <- R6Class(
  "Container",

  private = list(
    ..thing = thing_factory$new()
  ),

  active = list(
    thing = function(value) {
      if(missing(value)) {
        private$..thing
      } else {
        private$..thing <- value
      }
    }
  )

)

a_container <- container_factory$new()
a_clone <- a_container$clone()

a_container$thing$a_field <- "a new value" 
a_clone$thing$a_field

"a new value"

a_deep_clone <- a_container$clone(deep = TRUE)

a_container$thing$a_field <- "a different value" 
a_deep_clone$thing$a_field

"a new value"

Summary

R6 objects copy by reference
Copy them by value using clone()
clone() is autogenerated
clone(deep = TRUE) is for R6 fields

Let's practice!

Object-Oriented Programming with S3 and R6 in R

Cloning R6 Objects

clone() copies by value

Summary

Let's practice!

`clone()` copies by value