Non visible functions/methods in R -- how are they made?

function, hidden, methods, r

Solution

These are "hidden" functions. You might find this (warning pdf) useful. You can do it when you design a package in the NAMESPACE file included as part of the nuts and bolts of an R package. Here's the full text from the NAMESPACE file for the `bilan` package (can be found by opening up package source code tar.gz file from CRAN):

useDynLib(bilan)
exportPattern("^bil\\.[[:alpha:]]+")
exportPattern("^sbil\\.[[:alpha:]]+")

From the pdf mentioned above:

To have hidden functions. Replace the exportPattern command with an export command, where export's arguments are comma-separated function names that should be accessible to users

Basically, if you created an R package with two functions `foo` and `bar`, you could make NAMESPACE file with the line `export(foo)`, and then `bar` would be a hidden function.

Problem

How to define functions (methods) invisible to the user? Those which are asterisked when you call `methods()` on them. It seems there is everything about them on the internet, but how to define them? Can I just define a non-visible function (by adding something to its name for example), or should I tweak the environment somehow, or is it a particular feature of R packages to hide stuff?

Original source