On 11/09/2013 11:31 PM, Hadley Wickham wrote:
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.
Reference classes provide less memory copying and a more familiar programming
paradigm but not necessarily fantastic performance, as illustrated here
http://stackoverflow.com/questions/18677696/stack-class-in-r-something-more-concise/18678440#18678440
and I think elsewhere on this or the R-devel list (sorry not to be able to
provide a more precise recollection).
Martin
Hadley
On Sat, Nov 9, 2013 at 9:31 AM, daniel schnaider <dschnai...@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@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!
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