Copy function exactly, errors anyway - r

Question

I'm trying to plot indicators on a graph with quantmod. I have a few adjustments I want to make to the bbands function, but even if I copy the function exactly, I still get an error. Here were my steps:
type "addBBands"
control + c the code
type addBBands2 <- {copied code}
when trying to use the function this happens
Error in addBBands2() : could not find function "get.current.chob"
Here is the code
addBBands2<- function (n = 20, sd = 2, maType = "SMA", draw = "bands", on = -1)
function (n = 20, sd = 2, maType = "SMA", draw = "bands", on = -1)
{
stopifnot("package:TTR" %in% search() || require("TTR", quietly = TRUE))
draw.options <- c("bands", "percent", "width")
draw <- draw.options[pmatch(draw, draw.options)]
lchob <- get.current.chob()
x <- as.matrix(lchob#xdata)
chobTA <- new("chobTA")
if (draw == "bands") {
chobTA#new <- FALSE
}
else {
chobTA#new <- TRUE
on <- NULL
}
xx <- if (is.OHLC(x)) {
cbind(Hi(x), Lo(x), Cl(x))
}
else x
bb <- BBands(xx, n = n, maType = maType, sd = sd)
chobTA#TA.values <- bb[lchob#xsubset, ]
chobTA#name <- "chartBBands"
chobTA#call <- match.call()
chobTA#on <- on
chobTA#params <- list(xrange = lchob#xrange, colors = lchob#colors,
color.vol = lchob#color.vol, multi.col = lchob#multi.col,
spacing = lchob#spacing, width = lchob#width, bp = lchob#bp,
x.labels = lchob#x.labels, time.scale = lchob#time.scale,
n = n, ma = maType, sd = sd, draw = draw)
return(chobTA)
}
They aren't identical though somehow,
> str(addBBands)
function (n = 20, sd = 2, maType = "SMA", draw = "bands", on = -1)
> str(addBBands2)
function (n = 20, sd = 2, maType = "SMA", draw = "bands", on = -1)
- attr(*, "srcref")=Class 'srcref' atomic [1:8] 1 14 31 1 14 1 1 31
.. ..- attr(*, "srcfile")=Classes 'srcfilecopy', 'srcfile' <environment: 0x25eb9bf4>

Answer 1

I don't know quantmod, but presumably this is because get.current.chob is not exported from the package namespace. You could try referencing it with quantmod:::get.current.chob. There will probably be many such errors for other non-exported functions.

Answer 2

You need to ensure the function has the correct environment set so it can see non-exported functions.
Either copy the function (which will keep the environment):
addBBands2 <- addBBands
and then edit that.
Or change the environment directly after creating a new function. Consider:
f <- function() get.current.chob()
f()
Error in f() : could not find function "get.current.chob"
environment(f) <- environment(addBBands)
f()
An object of class "chob"
Slot "device":
...