>>>>> "PatBurns" == Patrick Burns <[EMAIL PROTECTED]>
>>>>> on Wed, 22 Sep 2004 18:30:10 +0100 writes:
PatBurns> If an attempt is made to attach to position 1, it
PatBurns> appears to work (not even a warning) but in fact
PatBurns> it doesn't work as many would expect. "search"
PatBurns> thinks that it gets placed in position 2, but
PatBurns> nothing is actually there (according to "ls").
PatBurns> This is guaranteed to be confusing (and annoying)
PatBurns> to people who are used to attaching to position 1
PatBurns> in S-PLUS.
yes; thanks for bringing this up!
PatBurns> I'm not clear on all of the implications of
PatBurns> changing this, but my first inclination would be
PatBurns> to make it an error to attach to position 1. The
PatBurns> help file says that you can't do it.
and has done so for a long time AFAIR.
PatBurns> At the very least there should be a warning . My
PatBurns> guess is that it is rare for someone to attach to
PatBurns> position 1 and not attempt to modify what is being
PatBurns> attached.
Hence (together with the arguments further above),
I think an error would be more appropriate
[if there's only a warning and the user's code continues on
the wrong assumption, more problems lay ahead].
OTOH, in the current "beta" phase I can think of a case where an
error would be too "hard":
The worst I can see is an R script that has attach(*, pos=1)
which doesn't attach at all {as you say, it *seems* to attach to
position 2 but doesn't really provide the object}, but for some
reason still continues to produce reasonable things.
Hene, for 2.0.0 in "deep freeze", I'd propose to give a warning only.
However, we wouldn't the database' to search()[2] "seemingly" only,
and this could be a problem if a user's script does a detach(..) later.
I.e., we should attach() to pos=2 *properly* (instead of
"seemingly") only.
At the latest for 2.1.0, we should rather make the warning an error.
In any case, this looks like a very simple fix (to the C
source);
Martin Maechler
>> attach('foo.RData')
>> search()
PatBurns> [1] ".GlobalEnv" "file:foo.RData" "package:methods"
PatBurns> [4] "package:stats" "package:graphics" "package:grDevices"
PatBurns> [7] "package:utils" "package:datasets" "Autoloads"
PatBurns> [10] "package:base"
>> ls(2)
PatBurns> [1] "jj"
>> jj
PatBurns> [1] 1 2 3 4 5 6 7 8 9
>> detach()
>> search()
PatBurns> [1] ".GlobalEnv" "package:methods" "package:stats"
PatBurns> [4] "package:graphics" "package:grDevices" "package:utils"
PatBurns> [7] "package:datasets" "Autoloads" "package:base"
>> attach('foo.RData', pos=1)
>> search()
PatBurns> [1] ".GlobalEnv" "file:foo.RData" "package:methods"
PatBurns> [4] "package:stats" "package:graphics" "package:grDevices"
PatBurns> [7] "package:utils" "package:datasets" "Autoloads"
PatBurns> [10] "package:base"
>> ls(2)
PatBurns> character(0)
PatBurns> _
PatBurns> platform i386-pc-mingw32
PatBurns> arch i386
PatBurns> os mingw32
PatBurns> system i386, mingw32
PatBurns> status Under development (unstable)
PatBurns> major 2
PatBurns> minor 0.0
PatBurns> year 2004
PatBurns> month 09
PatBurns> day 17
PatBurns> language R
______________________________________________
[EMAIL PROTECTED] mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
