is it possible to have an invisible function in R?

Question

I want to distribute an R object that is a function. For instance, say, here is my function:

f <- function(x) (x * x)
save(f, file = "f.rda")

Then,

load("f.rda")

gives me the function 'f', however, when I type

f
function(x) (x * x)

Is it possible to have this function f, but to hide what is in the source code.

I guess in some sense, I am probably asking for an equivalent to the pre-compiled "binary object file" without the source code.

Any suggestions will be greatly appreciated. I am not sure that this is necessarily possible.

My apologies, I do not quite understand how this will work. Can you give me an example using my function. To clarify, I want the f to do the calculation, but the source not to be available. I have looked at invisible earlier, but I did not figure out how to make it work for my case. — user3236841, Dec 04 '21 at 06:53
@user2864740, can you give me a simple example? I can not quite figure this out. — user3236841, Dec 04 '21 at 07:01

user2864740 · Accepted Answer · 2021-12-04T21:08:14.250

3

It should be possible to use a local environment / closure to do this. The following code uses a scoping assignment to expose f.

local({
g <- function (x) x * x; # "secret" algorithm!
f <<- function (x) g(x);
})

# g is not in scope here, although it is still bound in f's closure
f(4) # => 16

The result of print(f) only covers f itself only, and not the "secret" in g:

function (x) g(x)

This naturally won't hide the original file source or textual content itself.

As I don't actually use R, I've no idea if the environment can be reflected¹ to still expose g (and at some level it must be possible as a .rda file can be generated). However, this approach appears to fulfill the original requirement of not immediately exposing the algorithm.

¹As @HongOoi points out, the reflected environment (and g) can be accessed with environment(f)$g, which once again would expose the "secret".

edited Dec 04 '21 at 21:08

answered Dec 04 '21 at 07:16

user2864740

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`environment(f)$g` – Hong Ooi Dec 04 '21 at 07:43
@HongOoi Thanks - so enough to make looking a "purposeful intent" then. – user2864740 Dec 04 '21 at 07:45
@HongOoi, thank you! Very illustrative and nicely done. Though still retrievable, perhaps still useful. – user3236841 Dec 04 '21 at 14:45
Sorry, meant to thank @user2864740 for the code, but thanks also to HongOoi for the help. – user3236841 Dec 04 '21 at 17:16

is it possible to have an invisible function in R?

1 Answers1