R help - Nov 2003 - confint: which method attached?

the function
confint
uses the profiling method of the function of the package MASS
 
confint.glm

even after the package has been detached!

1: might this be the intenden behavior?

2. How does the function remember its 'MASS' functionality after
detaching the package?

R: 1.8.0; Windows 2000



Here is a sample program

> set.seed(7882)
> x<-rep(c(0,1),c(20,20))
> p<-plogis(2+0.1*x)
> y<-cbind(event,50-rbinom(length(p),50,p))
> xf<-factor(x)
> g<-glm(y~xf,family=binomial)
> 
> # conficence intervals according base package:
> print(confint(g))
                 2.5 %    97.5 %
(Intercept) 1.65425534 2.0266122
xf1         0.06324695 0.6282106
> 
> library(MASS)
> print(confint(g))
Waiting for profiling to be done...
                 2.5 %    97.5 %
(Intercept) 1.66398057 2.0247678
xf1         0.07341592 0.6210034
> 
> detach(package:MASS)
> print(search())
[1] ".GlobalEnv"      "package:methods"
"package:ctest"   "package:mva"
[5] "package:modreg"  "package:nls"    
"package:ts"      "Autoloads"
[9] "package:base"   
> print(confint(g))
Waiting for profiling to be done...
                 2.5 %    97.5 %
(Intercept) 1.66398057 2.0247678
xf1         0.07341592 0.6210034


Ulrich Halekoh, PhD
Institute of Agricultural Sciences, Biometry Group
8830 Tjele, Denmark,
ulrich.halekoh at agrsci.dk

On Mon, 17 Nov 2003, Ulrich Halekoh wrote:
> the function
> confint
> uses the profiling method of the function of the package MASS
>
> confint.glm
>
> even after the package has been detached!
Why the exclamation mark?  Note profile.glm is not actually in package:MASS
(sic).  Try looking for it:
> getAnywhere("profile.glm")
A single object matching 'profile.glm' was found
It was found in the following places
  registered S3 method for profile from namespace MASS
  namespace:MASS
with value
   ...
> 1: might this be the intenden behavior?
The accurate description is the intended behaviour.
> 2. How does the function remember its 'MASS' functionality after
> detaching the package?
It isn't in the package ....


There is currently no way to remove registered S3 methods like confint.glm
in an R session.  Nor is there likely to be in the near future,


General comment: R has changed quite a lot recently, and older
preconceptions do need to be checked against current information.
The article `Name Space Management for R' in R-news 2003/1 may help
(although it may tell you mor ethan you want to know).

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595