[R] detach

[Martyn Plummer]

My guess is that even though the zoo namespace is unloaded. The S3
method as.Date.numeric is still registered, and the name space will be
reloaded whenever it is dispatched.

> library(zoo)
> loadedNamespaces()
[1] "base"      "graphics"  "grDevices" "methods"   "stats"     "utils"
[7] "zoo"
> unloadNamespace("zoo")
<environment: namespace:zoo>
> loadedNamespaces() #Gone
[1] "base"      "graphics"  "grDevices" "methods"   "stats"     "utils"
> as.Date(1)
[1] "1970-01-02"
> loadedNamespaces() #Back again!
[1] "base"      "graphics"  "grDevices" "methods"   "stats"     "utils"
[7] "zoo"

So the question is whether there is a way to unregister an S3 method, so
that you can restore the method dispatching behaviour prior to the
package being loaded. I don't know the answer, but I'm guessing it's no.

On Wed, 2006-07-12 at 09:21 -0400, Gabor Grothendieck wrote:
> Note that even this entered into a fresh session exhibits this
> behavior.  There is no use of ::: here:
> 
> > as.Date(1)
> Error in as.Date.default(1) : do not know how to convert '1' to class "Date"
> > library(zoo)
> > as.Date(1)
> [1] "1970-01-02"
> > unloadNamespace("zoo")
> <environment: namespace:zoo>
> > as.Date(1)
> [1] "1970-01-02"
> > R.version.string
> [1] "Version 2.3.1 Patched (2006-06-04 r38279)"
> > packageDescription("zoo")$Version
> [1] "1.1-1"
> 
> On 7/12/06, Roger Peng <rdpeng at gmail.com> wrote:
> > I believe (3) should always work as long as zoo has a namespace.  The
> > ':::' operator will load the namespace of the package but will not
> > attach it to the search list.
> >
> > -roger
> >
> > On 7/11/06, Gabor Grothendieck <ggrothendieck at gmail.com> wrote:
> > > We try the following:
> > >
> > > search()
> > > as.Date(1)
> > > zoo:::as.Date.numeric
> > >
> > > under three circumstances:
> > >
> > > 1. on a fresh session
> > > 2. after issuing library(zoo) noting that as.Date.numeric is provided by zoo
> > > 3. after detaching zoo
> > >
> > > as.Date(1) fails on #1 but succeeds in #2 and #3.  Should it not fail in #3
> > > since zoo was detached?  Is this how its supposed to work?
> > >
> > > (Note that entering zoo:::as.Date.numeric at the console
> > > succeeds in displaying the function in all three cases.)
> > >
> > > Here is the console session:
> > >
> > > > R.version.string # XP
> > > [1] "Version 2.3.1 Patched (2006-06-04 r38279)"
> > > >
> > > > search()
> > > [1] ".GlobalEnv"        "package:methods"   "package:stats"
> > > [4] "package:graphics"  "package:grDevices" "package:utils"
> > > [7] "package:datasets"  "Autoloads"         "package:base"
> > > > as.Date(1)
> > > Error in as.Date.default(1) : do not know how to convert '1' to class "Date"
> > > > zoo:::as.Date.numeric
> > > function (x, ...)
> > > structure(floor(x + 0.001), class = "Date")
> > > <environment: namespace:zoo>
> > > >
> > > > library(zoo)
> > > > search()
> > >  [1] ".GlobalEnv"        "package:zoo"       "package:methods"
> > >  [4] "package:stats"     "package:graphics"  "package:grDevices"
> > >  [7] "package:utils"     "package:datasets"  "Autoloads"
> > > [10] "package:base"
> > > > as.Date(1)
> > > [1] "1970-01-02"
> > > > zoo:::as.Date.numeric
> > > function (x, ...)
> > > structure(floor(x + 0.001), class = "Date")
> > > <environment: namespace:zoo>
> > > >
> > > > detach()
> > > > search()
> > > [1] ".GlobalEnv"        "package:methods"   "package:stats"
> > > [4] "package:graphics"  "package:grDevices" "package:utils"
> > > [7] "package:datasets"  "Autoloads"         "package:base"
> > > > as.Date(1)
> > > [1] "1970-01-02"
> > > > zoo:::as.Date.numeric
> > > function (x, ...)
> > > structure(floor(x + 0.001), class = "Date")
> > > <environment: namespace:zoo>
> > > >
> > >
> > > ______________________________________________
> > > R-help at 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
> > >
> >
> >
> > --
> > Roger D. Peng  |  http://www.biostat.jhsph.edu/~rpeng/
> >
> 
> ______________________________________________
> R-help at 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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