Protecting function names in R

Question

Is it possible in R to protect function names (or variables in general) so that they cannot be masked.

I recently spotted that this can be a problem when creating a data frame with the name "new", which masked a function used by lmer and thus stopped it working. (Recovery is easy once you know what the problem is, here "rm(new)" did it.)

A data frame cannot overwrite a function. You can use both at the same time. — James, Aug 11 '10 at 08:43
Duplicate of http://stackoverflow.com/questions/936748/declaring-a-const-variable-in-r — hadley, Aug 13 '10 at 02:00

score 9 · Answer 1 · answered Aug 11 '10 at 09:46

9

There is an easy workaround for your problem, without worrying about protecting variable names (though playing with lockBinding does look fun). If a function becomes masked, as in your example, it is still possible to call the masked version, with the help of the :: operator.

In general, the syntax is packagename::variablename.

(If the function you want has not been exported from the package, then you need three colons instead, :::. This shouldn't apply in this case however.)

answered Aug 11 '10 at 09:46

Richie Cotton

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Doesn't work if I'm calling a function, in a package, which relies on a function elsewhere which inadvertently has become masked. – Andi F Aug 11 '10 at 14:56
@AndyF yeah that's a good point. I'm seeing a theme in the answers: R does not protect users from themselves. This is very Linux-like. ;) – JD Long Aug 12 '10 at 14:29

score 4 · Answer 2 · answered Aug 11 '10 at 00:35

4

Maybe use environments! This is a great way to separate namespaces. For example:

> a <- new.env()
> assign('printer', function(x) print(x), envir=a)
> get('printer', envir=a)('test!')
[1] "test!"

answered Aug 11 '10 at 00:35

Vince

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score 2 · Answer 3 · answered Aug 11 '10 at 09:34

2

@hdallazuanna recommends (via Twitter)

new <- 1
lockBinding('new', globalenv())

this makes sense when the variable is user created but does not, of course, prevent overwriting a function from a package.

answered Aug 11 '10 at 09:34

JD Long

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score 0 · Answer 4 · answered Jul 15 '22 at 20:10

I had the reverse problem from the OP, and I wanted to prevent my custom functions in .Rprofile from being overridden when I defined a variable with the same name as a function, but I ended up putting my functions to ~/.R.R and I added these lines to .Rprofile:

if("myfuns"%in%search())detach("myfuns")
source("~/.R.R",attach(NULL,name="myfuns"))

From the help page of attach:

One useful ‘trick’ is to use ‘what = NULL’ (or equivalently a
length-zero list) to create a new environment on the search path
into which objects can be assigned by assign or load or
sys.source.

...

## create an environment on the search path and populate it
sys.source("myfuns.R", envir = attach(NULL, name = "myfuns"))

Protecting function names in R

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