On 21 Feb 2003 at 18:06, [EMAIL PROTECTED] wrote:
The problem which surprised Brian Ripley (the search list being
changed by a package without the package giving information)
occurs also with recommended packages:
(This is R1.6.2)
> search()
[1] ".GlobalEnv" "package:ctest" "Autoloads" "package:base"
> library(nlme)
Loading required package: nls
Loading required package: lattice
> search()
[1] ".GlobalEnv" "package:mva" "package:lattice"
"package:grid"
[5] "package:nlme" "package:nls" "package:ctest" "Autoloads"
[9] "package:base"
mva and grid has been loaded without any warning. Everybody knows
lattice requires grid, but why mva?
Restarting R:
> search()
[1] ".GlobalEnv" "package:ctest" "Autoloads" "package:base"
> library(grid)
> search()
[1] ".GlobalEnv" "package:grid" "package:ctest" "Autoloads"
[5] "package:base"
> library(lattice)
> search()
[1] ".GlobalEnv" "package:lattice" "package:grid"
"package:ctest"
[5] "Autoloads" "package:base"
> library(nls)
> search()
[1] ".GlobalEnv" "package:nls" "package:lattice"
"package:grid"
[5] "package:ctest" "Autoloads" "package:base"
> library(nlme)
> search()
[1] ".GlobalEnv" "package:mva" "package:nlme"
"package:nls"
[5] "package:lattice" "package:grid" "package:ctest" "Autoloads"
[9] "package:base"
So nlme loads mva without a warning. This did'nt happen before
R1.6.0, I beleave.
On this theme, I have another question. I have a package
which needs another package (SuppDists) for only one
function. I do require() within that function only. Is that OK,
or should it be done within .First.lib ?
Kjetil Halvorsen
> There seems to be a widespread assumption that the way for package foo to
> require package bar is via `require(bar)'. It isn't!
>
> That returns a logical which is in the vast majority of cases unchecked.
> So if the package is really required, the code will fail without a warning
> if the package is unavailable. You may as well call library() and let it
> do the checking. (In a few cases you can safely assume that the package
> is present, e.g. nnet can require(MASS) since they are installed
> together.)
>
> I find it confusing if require(bar, quietly=TRUE) is used with no message.
> If you are going to change the search path, please let the end user know
> you have done so. I've had nasty surprises more than once from this by
> getting datasets from packages I did not ask to be there.
>
> Another point: please do not call code with side effects like require,
> library or options at the top level in foo/R/foo, but do so within
> .First.lib. This becomes important if the code is dumped or put in a
> database.
>
> --
> Brian D. Ripley, [EMAIL PROTECTED]
> 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 272866 (PA)
> Oxford OX1 3TG, UK Fax: +44 1865 272595
>
> ______________________________________________
> [EMAIL PROTECTED] mailing list
> http://www.stat.math.ethz.ch/mailman/listinfo/r-devel
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