RStudio and Lazy Evaluation - r

Question

I am mainting the package "hdm" and I encountered the following problem.
The following code runs in plain R and used to run in RStudio, but not anymore:
library(hdm)
attach(GrowthData)
fmla= "Outcome ~ ."
fmla.y= "Outcome ~ . - gdpsh465 "
rY= rlasso(fmla.y, data =GrowthData)
Error message:
Error in exists("homoscedastic", where = penalty) : object 'n' not
found
If no penalty in the function rlasso is specified it is set by default containing the variable "n", the sample size of x, which is evaluated later.
n is gotten by lazy evaluation and it seems that in RStudio the correct environment is not found anymore.
The error occurs here, but the problem is that penalty contains n which is not know
if (!exists("homoscedastic", where = penalty)) penalty$homoscedastic = "FALSE"
Somehow I am not sure to solve this and would like to ask if you have any idea.
Thanks a lot for your efforts in advance!
Best,
Martin

Answer 1

When x is a character object, the problem arises because n is not defined in the environment from which rlasso.formula is called, i.e. rlasso.character(), or its parents. This is roughly what's happening:
test <- function(x, ...) {
UseMethod("test")
}
test.character <- function(x, pen = list(alpha = n)) {
test.formula(x, pen = pen)
}
test.formula <- function(x, pen = list(alpha = n)) {
n <- 2
test.default(x, pen)
}
test.default <- function(x, pen = list(alpha = n)) {
n <- 3
exists("alpha", where = pen)
}
test("y ~ x")
# Error in exists("alpha", where = pen) : object 'n' not found
test(y ~ x)
# [1] TRUE
test(123)
# [1] TRUE
A workaround is to not specify pen in the call to the formula method if it's not defined when the character method is called:
test.character <- function(x, pen = list(alpha = n)) {
if (missing(pen))
test.formula(x)
else
test.formula(x, pen = pen)
}
test("y ~ x")
# [1] TRUE