Can an object reference itself?
On Fri, Jan 15, 2010 at 5:30 PM, Janko Thyson
<janko.thyson at ku-eichstaett.de> wrote:
Dear List,
I am not really familiar with any other language than R, but I?ve heard that
in other languages there is something called ?self referencing?.
Here?s what I?m trying to get an answer for:
Suppose there is a function that takes as its input a value of a slot of an
S4 object. The function itself is stored in another slot of the SAME S4
object. Is it then possible to have the function automatically ?recognize?
the name of the object in which slot it is placed via some sort of ?self
referencing? of the S4 object (to avoid having to explicitly state the
required function argument for different S4 object instances with different
names)?
I hope the following code snippets will give you an idea what I?m trying to
do:
obj.for.slot <- data.frame(a=1); obj.for.slot <- data.frame(a=100)
save(obj.for.slot, file="C:/obj.1.for.slot.Rdata"); save(obj.for.slot,
file="C:/obj.2.for.slot.Rdata")
slotfun <- function(obj.name)
{
? ? ? ?file.fqn.char <- paste("file.fqn <- ", obj.name, "@file.fqn",
sep="")
? ? ? ?eval(parse(text=file.fqn.char))
? ? ? ?load(file=file.fqn)
? ? ? ?return(obj.for.slot)
}
setClass(
? ? ? ?Class="Testclass",
? ? ? ?representation=representation(
? ? ? ? ? ? ? ?file.fqn="character",
? ? ? ? ? ? ? ?data="function"
? ? ? ?),
? ? ? ?prototype=prototype(
? ? ? ? ? ? ? ?file.fqn="blabla",
? ? ? ? ? ? ? ?data=slotfun
? ? ? ?)
)
test ? ? ? ? ? ?<- new("Testclass")
test.mod ? ? ? ?<- new("Testclass")
test at file.fqn ? ? ? ? ? <- "C:/obj.1.for.slot.Rdata"
test.mod at file.fqn ? ? ? <- "C:/obj.2.for.slot.Rdata"
test at data(obj.name="test")
test.mod at data(obj.name="test.mod")
An object does not have a unique name. What would happen in the following situations? t3 <- test.mod tests <- list( test, test.mod ) Hadley