I would like to pass a reference class to a reference class constructor, and assign the passed reference class as a field. However, when I run the code below, I don't understand why I get an error. My questions are:
1) Please can someone kindly explain why this error is occurring:
> a <- ClassA&new()
Error in .getClassFromCache(Class, where) :
argument "Class" is missing, with no default
> b <- ClassB$new(a)
Error in .Object$initialize(...) : object 'a' not found
2) I have declared class.a.container as class "list", however I want this to be a reference class. What do I need to put here instead of "list" ?
ClassA <- setRefClass(
"ClassA",
fields = list(myVar = "numeric"),
methods = list(
someMethod = function(){
print("hi")
}
)
)
ClassB <- setRefClass(
"ClassB",
fields = list(class.a.container = "list"),
methods = list(
initialize = function(class.a){
class.a.container <<- class.a
})
)
a <- ClassA&new()
b <- ClassB$new(a)
Y'er gonna feel kind of silly, at least I did when I noticed the problem. You have an ampersand insead of a dollar-sign in the extraction from the envirnment-class-item.
a <- ClassA$new(myVar=1)
a$someMethod(2)
#[1] "hi
42- has already pointed out one error in your code (& instead of $).
To fully answer your original question, I just want to explicitly point out that after correcting that bug, you then need to change the declaration of the field in ClassB from
class.a.container = "list"
to
class.a.container = "ClassA"
Here is complete code that works for me:
ClassA = setRefClass(
Class = "ClassA",
fields = list(myVar = "numeric"),
methods = list(
someMethod = function() {
print("hi")
}
)
)
ClassB = setRefClass(
Class = "ClassB",
fields = list(class.a.container = "ClassA"),
methods = list(
initialize = function(class.a) {
class.a.container <<- class.a
}
)
)
a = ClassA$new(myVar = 1)
a
b = ClassB$new(a)
b
It prints:
...
> a
Reference class object of class "ClassA"
Field "myVar":
[1] 1
>
> b = ClassB$new(a)
> b
Reference class object of class "ClassB"
Field "class.a.container":
Reference class object of class "ClassA"
Field "myVar":
[1] 1