[R] S4; Setter function is not chaning slot value as expected

[Hadley Wickham]

Modelling a mutable entity, i.e. an account, is really a perfect
example of when to use reference classes.  You might find the examples
on http://adv-r.had.co.nz/OO-essentials.html give you a better feel
for the strengths and weaknesses of R's different OO systems.

Hadley

On Sat, Nov 9, 2013 at 9:31 AM, daniel schnaider <dschnaider at gmail.com> wrote:
> It is my first time programming with S4 and I can't get the setter fuction
> to actually change the value of the slot created by the constructor.
>
> I guess it has to do with local copy, global copy, etc. of the variable -
> but, I could't find anything relevant in documentation.
>
> Tried to copy examples from the internet, but they had the same problem.
>
> # The code
>     setClass ("Account" ,
>                representation (
>                customer_id = "character",
>                transactions = "matrix")
>     )
>
>
>     Account <- function(id, t) {
>             new("Account", customer_id = id, transactions = t)
>             }
>
>
>     setGeneric ("CustomerID<-", function(obj,
> id){standardGeneric("CustomerID<-")})
>     setReplaceMethod("CustomerID", "Account", function(obj, id){
>         obj at customer_id <- id
>         obj
>         })
>
>         ac <- Account("12345", matrix(c(1,2,3,4,5,6), ncol=2))
>         ac
>         CustomerID <- "54321"
>         ac
>
> #Output
>         > ac
>         An object of class "Account"
>         Slot "customer_id":
>         [1] "12345"
>
>         Slot "transactions":
>              [,1] [,2]
>         [1,]    1    4
>         [2,]    2    5
>         [3,]    3    6
>
> # CustomerID is value has changed to 54321, but as you can see it does't
>         > CustomerID <- "54321"
>         > ac
>         An object of class "Account"
>         Slot "customer_id":
>         [1] "12345"
>
>         Slot "transactions":
>              [,1] [,2]
>         [1,]    1    4
>         [2,]    2    5
>         [3,]    3    6
>
>
> Help!
>
>         [[alternative HTML version deleted]]
>
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-- 
Chief Scientist, RStudio
http://had.co.nz/