If you want to use this pattern repeatedly you can define something like
makeFunWithCounter <- function(fun) {
counter <- 0
list(count = function() counter,
fun = function(...) { counter <<- counter + 1; fun(...)})
}
and then do
> fwc <- makeFunWithCounter(function() print("Hello"))
> f2 <- fwc$fun
> f2()
[1] "Hello"
> f2()
[1] "Hello"
> f2()
[1] "Hello"
> fwc$count()
[1] 3
If you only want to do it once you can use local,
fwc <- local({
counter <- 0
fun <- function() { counter <<- counter + 1; print("Hello") }
list(count = function() counter, fun = fun)
})
Best,
luke
On Fri, 29 Aug 2008, Giles Hooker wrote:
Thanks,
I think I over-emphasized the secondary function, but I can generate the
scoping problem as follows. First, at the command line, I can get a function
to access objects that were not in its arguments by
ProfileEnv = new.env()
hello.world = "Hello World"
assign('hello.world',hello.world,3,envir=ProfileEnv)
fn1 = function()
{
hw = get('hello.world',envir=ProfileEnv)
print(hw)
}
and then call
fn1()
[1] "Hello World"
Now I want to define a wrapper function
fn2 = function()
{
ProfileEnv = new.env()
hello.world = "Hello World"
assign('hello.world',hello.world,3,envir=ProfileEnv)
fn1()
}
and if I try
rm(ProfileEnv) # Just to be safe
rm(hello.world)
fn2()
Error in get("hello.world", envir = ProfileEnv) :
object "ProfileEnv" not found
In my actual code, fn1() is really a call to
optim(pars,ProfileErr,....)
and hello.world are quantities that were calculated the last time that
ProfileErr was called and that I want to keep track of.
As an alternative simple example, how would I keep a counter for the number
of times that optim (or any other generic optimizer) has called ProfileErr?
giles
How can I define environments within a function so that they are visible
to calls to a sub-function?
I think you need to give a simplified, runnable example. (Or at least
runnable until it hits the scoping problem you've got.) "Sub-function"
isn't R terminology, and it's not clear what you mean by it.
--
Luke Tierney
Chair, Statistics and Actuarial Science
Ralph E. Wareham Professor of Mathematical Sciences
University of Iowa Phone: 319-335-3386
Department of Statistics and Fax: 319-335-3017
Actuarial Science
241 Schaeffer Hall email: [EMAIL PROTECTED]
Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu
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