Re: [R] Validity check when setting slot

[Renaud Gaujoux]

It looks like a sound solution.
Thanks Vitalie.

Vitalie S. wrote:

Hi,

    RG> Hi,
    RG> I'm wondering if the following behaviour is normal:

RG> setClass('A', representation(number='numeric'), RG> validity=function(object){ RG> if( obj...@number < -1 ) return("Invalid number"); TRUE})

    >> [1] "A"
    RG> a <- new('A')
    RG> a
    >> An object of class “A”
    >> Slot "number":
    >> numeric(0)

    RG> a...@number <- 0
    RG> a...@number <- -3
    RG> a
    >> An object of class “A”
    >> Slot "number":
    >> [1] -3

Rewriting `@<-` will do the job:

setClass('A', representation(number='numeric'),
          validity=function(object){
                        if( obj...@number < -1 ) return("Invalid number")
                        TRUE}
)


setMethod("@<-",
    signature(object = "A"),
    function (object, name, value){

object <- callNextMethod(object, as.character(substitute(name)), value)

        validObject(object)
        return(object)
    }
)

a <- new('A')
a...@number <- 23
a...@number <- -23

Error in validObject(object) : invalid class "A" object: Invalid number


By th way, it seems (to me) that there is a bug in callNextMethod above:

        object <- callNextMethod(object, name, value)
or
        object <- callNextMethod()

trigger an error:

Error in checkSlotAssignment(object, name, value) :
  "name" is not a slot in class "A"

-Vitalie

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