[R] How to get the namespace of a function?

[Fernando Saldanha]

I am trying to imitate "encapsulation" from other languages like Java
or C++. Coming from that background, it bothers me that I can commit
errors like the following:

> x <- 1
> f <- function(z) { y <- x; y + 1 } # Mistake: I should have written y <- z
> f(10)
[1] 2

In a language like Java the interpreter would have noticed that x was
an undeclared variable and an error message would be issued. R, on the
other hand, allows the code to run, as x exists in the global
environment. I was trying to avoid such situations by  setting the
environment of f to be NULL. If there is a better way to catch this
type of errors I would be interested in knowing about it.

FS

On 2/2/06, Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> On 2/2/2006 10:56 AM, Fernando Saldanha wrote:
> > I declared the environment of the function myfun to be NULL as follows:
> >
> > environment(myfun) <- NULL
>
> Since version 2.1.0, it's been recommended that you use
>
> environment(myfun) <- baseenv()
>
> and since 2.2.0, you'll get a warning when using NULL (and you'll get an
> error in 2.3.0).  But why would you want to do that?  What are you
> trying to achieve?
>
> Duncan Murdoch
>
>
> >
> > Later on I called that myfun and got an error message because the
> > function index() in the zoo package was called inside myfun and was
> > not visible:
> >
> > Error in myfun(args) : couldn't find function "index"
> >
> > I tried to use zoo::index() instead of index(), but that did not work.
> > In fact, zoo::index does not work even in the command line:
> >
> >> z<-ts(1:5)
> >> z
> > Time Series:
> > Start = 1
> > End = 5
> > Frequency = 1
> > [1] 1 2 3 4 5
> >> index(z)
> > [1] 1 2 3 4 5
> >> zoo::index(z)
> > Error in loadNamespace(name) : package 'zoo' does not have a name space
> >
> > How can I qualify index() so that it is visible inside the body of myfun?
> >
> > Thanks for any suggestions,
> >
> > FS
> >
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