3 messages · Erich Neuwirth, Brian Ripley, Peter Dalgaard
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?
Erich Neuwirth, Computer Supported Didactics Working Group Visit our SunSITE at http://sunsite.univie.ac.at Phone: +43-1-4277-38624 Fax: +43-1-4277-9386
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 with().
Brian D. Ripley, ripley@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 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
Prof Brian D Ripley <ripley@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 with().
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@biostat.ku.dk) FAX: (+45) 35327907