Functions not finding variables, or environment, when inside a foreach loop

Question

I'm attempting to build an R package that contains a top level function inside a couple of nested foreach loops. This top level function then calls a set of further nested functions. The problem I've got is of lexical scoping, the lower level functions can not find either the environment where I put the variables, or the variables. I've attempted to use attach, as per this example attach but lower functions can still no not see necessary arguments. I know there is something specific about doMPI using a forking method. This is on Ubuntu Linux (16.04), using doMPI (0.2.2) and foreach (1.4.3) and openmpi. This is a mwe of a much bigger model that I have. The package, and a script to run/test it called toymod4 package are available for download.

#' Test function level 1
#' @param num.sim first variable for function 1
#' @param num.per second variable for function 1
#' @param num.day third variable for function 1
#' @param fun2.params parameters for function 2
#' @param fun31.params parameters for first call of function 3
#' @param fun32.params parameters for second call of funtion 3
#' @param fun4.params parameters for call to function 4
#' @export fun1
fun1 <- function (fun2.params, fun31.params, fun32.params, fun4.params,
                  num.sim=10, num.per=8, num.day=5, ...) {
    final.results <- data.frame (foreach::`%dopar%`(
        foreach::`%:%`(foreach::foreach(j = 1:num.sim,
                                        .combine = cbind,
                                        .packages= c("toymod4")),
                       foreach::foreach (i = 1:num.per,
                                         .packages = c("toymod4"),
                                         .combine=rbind)), {
            e1 <- new.env()
            e1 <- list2env(c(fun2.params, fun31.params, fun32.params,
                             fun4.params), e1)
            out3 <- replicate(num.day, fun2(e1, var21, var22, fun22on))
            out2 <- data.frame(mean(out3))
        }
    )
    )
    ## save outputs for subsequent analyses if required
    saveRDS(final.results, file = paste(num.day ,"_", num.per, "_", num.sim, "_",
                                        format(Sys.time(), "%d_%m_%Y"),
                                        ".rds", sep=""))
    return(final.results)
}

#' Test function level 2
#' @param var21 first variable for function 2
#' @param var22 second variable for function 2
#' @param fun22on turn this copy of fun3 on or off
#' @param env environment to get variables from 
#' @export fun2
fun2 <- function (env, var21, var22, fun22on, ...) {
    attach(env)
    out21 <- ifelse (rpois(1, var21) > 0, var22 * fun3(e1, fun3on, var31), 0)
    out22 <- ifelse (fun22on, fun3(e1, fun3on, var31), 0)
    out2 <- out21 + out22
    detach(env)
    out2
}

#' Test function level 3
#' @param var31 first variable for function 3
#' @param fun3on turn the formula on or off
#' @export fun3
fun3 <- function (env, fun3on, var31, ...) {
    attach(env)
    out31 <- ifelse (fun3on, var31, 1)
    out32 <- ifelse (fun3on, fun4(e1, fun4on, var41), 0)
    out3 <- out31 + out32
    detach(env)
    out3
}

#' Test function level 4
#' @param var41 first variable for function 4
#' @param fun4on turn the formula on or off
#' @export fun4
fun4 <- function (env, fun4on, var41, ...) {
    attach(env)
    out4 <- ifelse (fun4on, var41, 1)
    detach(env)
    out4
}

Answer 1

I've managed to get a solution to this problem, with the generous help of Steve Weston. Rather than try to explain it all, I've posted it on github at this address https://github.com/jamaas/VarPasMpiExamp.git It is one way to pass variable values to functions that are contained within a foreach loop. In theory, it should work for R, foreach on any operating system, using any parallel backend, however has not been tested on all as yet. The development and testing of this version was done on Ubuntu 16.04 (Debian) Linux. Let me know if this method works for you, or particularly if you have a simpler, more elegant solution.