[R] Creating S4 class with a slot as an array

[Morgan, Martin]

> -----Original Message-----
> From: R-help [mailto:r-help-bounces at r-project.org] On Behalf Of Glenn
> Schultz
> Sent: Tuesday, October 20, 2015 10:36 AM
> To: R Help R
> Subject: [R] Creating S4 class with a slot as an array
> 
> Hello All,
> 
> I am trying to create an S4 class with a slot that is an array.  Below is the code I
> tried but I have missed something.  Any suggestions are appreciated.
> 
> setClass("CashFlow",
> representation(
> CashFlowArray = "array"))

probably here you would also like to provide a prototype

 setClass("CashFlow",
      representation(CashFlowArray="array"),
      prototype=prototype(CashFlowArray=array(numeric(), c(0, 0, 0))))

> 
> setMethod("initialize",
> signature = "CashFlow",
> function(.Object,
> CashFlowArray = "array"
> ){

.Object is the prototype, so the next line...

> .Object at CashFlowArray

references the prototypes' default value for the slot, without modifying it, and then...

> return(.Object)

returns the unmodified object, never getting to the following line...

> callNextMethod(.Object,...)

which would have passed the prototype and all arguments that are _not_ CashFlowArray on to the default 'initialize' method.

Maybe you meant

setMethod("initialize", "CashFlow", function(.Object, ..., CashFlowArray=array()) {
    callNextMethod(.Object, ..., CashFlowArray=CashFlowArray)
})

or, since the initialize method is now not doing anything, simply not defining it in the first place.

Martin Morgan

> })
> CashFlow <-function(CashFlowArray = array()){ new("CashFlow",
> CashFlowArray = CashFlowArray) }
> 
> CFTest <- array(data = 2, c(360,8))
> 
> Test <- CashFlow(CashFlowArray = CFTest)
> 
> Thanks,
> Glenn
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