I am not sure what the purpose of workspace is so I
have eliminated it in the following. We just use the
environment within main and when main exits all its
variables go too so that seems sufficient.
fun.global <- function() { message('fun.global'); setVar(5) }
main <- function() {
l.var <- 0
setVar <- function(value) { message("set Var"); l.var <<- value }
environment(fun.global) <- environment()
fun.global()
print(l.var)
}
main()
We could also recognize that there is an implicit object here with
methods setVar and fun.global and property l.var so using proto:
library(proto)
fun.global <- function(obj) { message("setVar"); obj$setVar(5) }
main <- function() {
p <- proto(l.var = 0,
setVar = function(obj, value) { message("setVar");
obj$l.var <- value },
fun.global = fun.global)
p$fun.global()
print(p$l.var)
}
main()
On Thu, Aug 20, 2009 at 4:27 AM, Renaud Gaujoux<geto...@gmail.com> wrote:
> Hi,
>
> in my project I want the user to be able to write hook functions that are in
> turn called in my main code. I'd like the user's hooks to be able to call
> some function that set a variable outside their running environment. The
> trick is that this variable is not global, but defined on runtime before
> calling the hooks, and I don't want to leave any trace (i.e. global
> variables) after the main code has finished.
>
> I thought that the following would work but it doesn't. I guess I got too
> messy with environment and enclosures:
>
> # global function defined by the user
> fun.global <- function(){
> message('fun.global')
> setVar(5) #
> }
>
>
> # my main code
> main <- function(){
> message('main')
>
> # define a function to set some local variable
> setVar <- local({
> l.var <- 0
> function(value){
> message('setVar')
> l.var <<- value
> }
> })
> .workspace <- environment(setVar)
> environment(setVar) <- new.env()
>
> eval(fun.global(), enclos=environment(setVar))
> print(get('l.var', envir=.workspace, inherits=FALSE))
> }
>
> main()
>
> I get the following output:
>> main
>> fun.global
>> Error in fun.global() : could not find function "setVar"
>
> There is definitely a problem of lookup somewhere. I first tried without
> eval, as I thought that function setVar would then be defined in a parent
> environment of the call to fun.global, but it does not work either.
> Can anybody tell me what's the problem and how I should do my stuff?
>
> Thanks,
> Renaud
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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>
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