Patch base::library with wrapper in R - r

Question

Inside an R package, I'm trying to patch the base::library() function in R to specifically set the position of the loaded packages in the search path. I haveve defined several environments (all named env:<something>) and want to make sure that libraries are placed below these environments in the search path.
# wrap around library function.
library = function(..., pos = NULL) {
print("NEW LIBRARY FUNCTION!")
if (is.null(pos)) {
pos <- grep("env:", search())
pos <- if (length(pos) == 0) 2 else max(pos) + 1
}
base::library(..., pos=pos)
}
When I assign this function in the console, everything runs fine:
> library(stats)
[1] "NEW LIBRARY FUNCTION!"
> eval(parse(text = "library(stats)"))
[1] "NEW LIBRARY FUNCTION!"
> eval(parse(text = "library(stats)"), envir = globalenv())
[1] "NEW LIBRARY FUNCTION!"
When I define the above wrapper function inside my package, build it and load it in a new R Session, the following executes as expected:
> library(mypackage)
> mypackage:::library(stats)
[1] "NEW LIBRARY FUNCTION!"
But, when using eval() with the envir argument inside a function in mypackage, my new definition of library() is not retrieved:
# Functions defined in mypackage
testlibrary1 = function(...) {
library(...)
}
testlibrary2 = function(code) {
eval(parse(text = code))
}
testlibrary3 = function(code) {
eval(parse(text = code), envir = globalenv())
}
In console, I get the following results:
> mypackage:::testlibrary1(stats)
[1] "NEW LIBRARY FUNCTION!"
> mypackage:::testlibrary2("library(stats)")
[1] "NEW LIBRARY FUNCTION!"
> mypackage:::testlibrary3("library(stats)")
>
The last function, testlibrary3(), did not use the new wrapper function.
I want all functions that call library() inside mypackage to use my wrapper function. Can somebody help me out?

Answer 1

I guess the problem is the following, but as your question did not include a fully reproducible example (i.e., by uploading the package somewhere) it is difficult to tell.
As long as your library function is not exported from your package via the NAMESPACE it is not visible. Consequently, the only available library function to eval is base::library().
Note that while your function resides in the namespace of the package the calling environment for mypackage:::testlibraryX() is still the global environment. There your library functions is not available. Try to export is and see if this helps.