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

From: Gabor Grothendieck <ggrothendieck_at_gmail.com>
Date: Fri 03 Feb 2006 - 10:16:09 EST

I don't want to put words in anyone's mouth but I don't think the poster was voicing an unfair criticism so much as explaining his expectation coming from a java background.

On 2/2/06, Berton Gunter <gunter.berton@gene.com> wrote:
> Just echoing and slightly amplifying Gabor's comment...
>
> The semantics of R are really based on functional programming (LISP-like)
> rather than OOP (JAVA-like)? R's behavior is "proper" from that point of
> view; what is "improper" is Fernando's expectation that it should behave
> some other way. Of course, one can simulate anything with a Turing machine,
> but I consider Fernando's criticisms somewhat "unfair" because he is
> expecting R to behave like something he is familiar with rather than as it
> was designed to. For this reason, what bothers him seems wholly desirable to
> me -- I want there to be well-defined scoping convention (lexical scoping)
> for R to find free variables.
>
> Cheers,
>
> Bert
>
>
>
> -----Original Message-----
> From: r-help-bounces@stat.math.ethz.ch
> [mailto:r-help-bounces@stat.math.ethz.ch] On Behalf Of Duncan Murdoch
> Sent: Thursday, February 02, 2006 2:16 PM
> To: fsaldanha@alum.mit.edu
> Cc: r-help@stat.math.ethz.ch
> Subject: Re: [R] How to get the namespace of a function?
>
> On 2/2/2006 5:05 PM, Fernando Saldanha wrote:

> > 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.
>
> Put your code in a package, and use a namespace. This isn't perfect,
> but it gives you more control than you have when running scripts at the
> console.
>
> There's an article by Luke Tierney in one of R News 3/1 that explains
> the search order when namespaces are involved.
>
> Duncan Murdoch
> >
> > FS
> >
> > On 2/2/06, Duncan Murdoch <murdoch@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
> >>>
> >>> ______________________________________________
> >>> R-help@stat.math.ethz.ch mailing list
> >>> https://stat.ethz.ch/mailman/listinfo/r-help
> >>> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
> >>
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html Received on Fri Feb 03 10:24:17 2006

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