Pass Object (DF) to Custom Function Stored in Script - r

Question

How do I pass a pre-existing object, such as a DF, to my custom functions, given the setup I have (see below)?
Alternatively, do I need to set up my custom functions differently?
My functions reside in a series of *.R scripts.
I source the functions in my .Rprofile:
.env$fxShortName <- function(){
source("C:\\path\\to\\scriptFile.R")
}
Not-Quite Solutions:
1) Defining the Function Manually || It works w/ the obvious drawback that I need to manually load my functions each time.
2) Rscript + commandArgs || This works if I define the DF within the function, like this:
#foo.R
a <- data.frame(a = c(1))
b <- data.frame(b = c(1))
args <- commandArgs(trailingOnly = TRUE)
print(args)
data.frame.name <- args[1]
print(colnames(get(data.frame.name)))
Rscript creates a new R instance, though, so it doesn't see my pre-existing DF. At least, it doesn't find it out-of-the-box.
3) Function w/ substitute, match.call, etc. || I've adopted %>>% to set up auto-updated views of certain DFs, so I tried modifying the setup that works in that case. For %>>% I have this code in my .Rprofile:
.env$`%>>%` <- function(expr, x) {
x <- substitute(x)
call <- match.call()[-1]
fun <- function() {NULL}
body(fun) <- call$expr
makeActiveBinding(sym = deparse(x), fun = fun, env = parent.frame())
invisible(NULL)
}
This type of setup works with DFs from my current session. However, I prefer the structure offered by keeping my custom scripts separate from my .Rprofile.
4) get() & mget() || This seemed promising, but I don't understand it enough to definitively say whether or not it will help. And, yes, I did RTFM.
Reproducible Example:
myfx(head, preExistingDF)
Sample Code:
myfx <- function(expr, x) {
x <- substitute(x)
call <- match.call()[-1]
fun <- function() {NULL}
body(fun) <- call$expr
print(body(fun))}
Put the sample code in a script. Add the following code to your .Rprofile:
.env$mySamplefx <- function(){
source("C:\\path\\to\\myfx.R")
}
Then try it after adding the code directly to your .Rprofile.