S4 class slot type S4 class

All,

I am considering creating an S4 class whose slots (2) are both S4 
classes. ?Since an S4 slot can be an S3 class I figure this can be done. 
 ?However, the correct syntax of which I am unsure. ?Reviewing the docs 
I have come to the following conclusion:

SetClass('myfoo',
 ? ? ? ? ? ? ? ? ? slots = (foo1, foo2))

Without a type I believe each slot is .Data. ?A get method on the above 
class slots would return say foo1 which will have all methods and 
generics belonging to foo1 class. ?Is this the correct approach?

Suppose you have two classes

   .A = setClass("A", slots = c(x = "numeric"))
   .B = setClass("B", slots = c(y = "numeric", z = "numeric"))

A third class containing these would be

   .C = setClass("C", slots = c(a = "A", b = "B"))

where names of the slot argument are the slot names, and the character 
strings "A", "B" are the type of object the slot will store.

 > .C()
An object of class "C"
Slot "a":
An object of class "A"
Slot "x":
numeric(0)


Slot "b":
An object of class "B"
Slot "y":
numeric(0)

Slot "z":
numeric(0)


 > .C(a = .A(x = 1:2), b = .B(y = 2:1, z = 1:2))
An object of class "C"
Slot "a":
An object of class "A"
Slot "x":
[1] 1 2


Slot "b":
An object of class "B"
Slot "y":
[1] 2 1

Slot "z":
[1] 1 2



Martin Morgan

Best,
Glenn

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