[Rd] attach behavior
p.dalgaard at biostat.ku.dk
Sun Aug 29 09:26:08 CEST 2004
Prof Brian D Ripley <ripley at stats.ox.ac.uk> writes:
> On Sun, 29 Aug 2004, Erich Neuwirth wrote:
> > In R 1.9.1, attaching an object more than once puts the object's name on
> > the search path more than once also. Therefore, to remove it, one has to
> > detach it multiply.
> > Wouldn'tn it make sense to change the behavior of attach in a way
> > that object names are not added to the search path more than once?
> They need not be the same object, so no. It's quite common practice to
> modify an object, attach it temporarily and detach it again. I suspect
> that people using attach() frequently should be thinking more in terms of
That's one argument. Another is that attach(foo) followed by detach()
should leave the search path unchanged. I.e. if attach() is sometimes
a NOP, we must arrange so that the next detach() is one too. You could
do that I suppose, but then there's code that acts depending on what
it finds in search(), and...
Or, briefly: That way lies madness!
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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