How to pass object in nested functions? - r

Question

I'm trying to override save() in R so that it creates any missing directories before saving an object. I'm having trouble passing an object through one function to another using the ellipsis method.
My example:
save <- function(...,file){ #Overridden save()
target.dir <- dirname(file) #Extract the target directory
if(!file.exists(target.dir)) {
#Create the target directory if it doesn't exist.
dir.create(target.dir,showWarnings=T,recursive=T)
}
base::save(...,file=file.path(target.dir,basename(file)))
}
fun1 <- function(obj) {
obj1 <- obj + 1
save(obj1,file="~/test/obj.RData")
}
fun1(obj = 1)
The code above results in this error:
Error in base::save(..., file = file.path(target.dir, basename(file))) :
object ‘obj1’ not found
I realize that the problem is that the object 'obj1' doesn't exist inside my custom save() function, but I haven't yet figured out how to pass it from fun1 to base::save.
I have tried:
base::save(parent.frame()$...,file=file.path(target.dir,basename(file)))
and:
base::save(list=list(...),file=file.path(target.dir,basename(file)))
with no success.
Any suggestions?

Answer 1

You need to specify the parent's environment to 'base::save' :
save <- function(...,file){ #Overridden save()
target.dir <- dirname(file) #Extract the target directory
if(!file.exists(target.dir)) {
#Create the target directory if it doesn't exist.
dir.create(target.dir,showWarnings=T,recursive=T)
}
base::save(...,file=file.path(target.dir,basename(file)),envir=parent.frame())
}
Note the parameter added to the base::save call.
fun1 <- function(obj) {
obj1 <- obj + 1
save(obj1,file="~/test/obj.RData")
}
In addition, use '=' to specify parameter names:
fun1(obj = 1)