> -----Original Message----- > From: l...@stat.uiowa.edu [mailto:l...@stat.uiowa.edu] > Sent: Friday, March 12, 2010 4:24 PM > To: William Dunlap > Cc: r-devel@r-project.org > Subject: Re: [Rd] symbol name caching bug: attributes get > tied to symbol names > > Since symbols/names are reference objects this behavior in unavoidable > if we allow attributes to be added to them. On the other hand, I'm > not sure it makes sense to allow that. Attempting to set an attribute > on NULL signals an error; it would probably make sense to do the same > for any name object. >
Thanks Luke, for the explanation. I'm comfortable disallowing attributes on names. The problem arose for me when analyzing a parse tree and I was using attributes to label parts of it. I can stick in a list() layer above the calls, names, etc., to attach the attributes to. That can simplify the syntax also, since things like as.vector() applied to a call object with attributes won't strip the attributes. Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > luke > > On Fri, 12 Mar 2010, William Dunlap wrote: > > > In R versions 2.10.1 and "2.11.0 Under development > > (unstable) (2010-03-07 r51225)" on Windows I get the > > following if I type the commands at the start of > > the session. Note how the attribute attached to > > the name "Response" by the initial call to structure() > > seems to get tied to that name for the remainder of > > the session: > > > > > z <- structure(quote(Response), isResponse=TRUE) > > > parse(text="Response~Predictor")[[1]][[2]] > > Response > > attr(,"isResponse") > > [1] TRUE > > > quote(Response~Predictor)[[2]] > > Response > > attr(,"isResponse") > > [1] TRUE > > > quote(Response) > > Response > > attr(,"isResponse") > > [1] TRUE > > > > The attribute actually does go away after quite a > > while, but I haven't figured out the trigger. > > rm(z) followed by gc() does not affect it. > > > > If I use an unadorned variable called Response before > > making the structure z, then the isResponse attribute > > doesn't seem to stick to the name Response. > > > > > > Bill Dunlap > > Spotfire, TIBCO Software > > wdunlap tibco.com > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > > > -- > Luke Tierney > Chair, Statistics and Actuarial Science > Ralph E. Wareham Professor of Mathematical Sciences > University of Iowa Phone: 319-335-3386 > Department of Statistics and Fax: 319-335-3017 > Actuarial Science > 241 Schaeffer Hall email: l...@stat.uiowa.edu > Iowa City, IA 52242 WWW: http://www.stat.uiowa.edu > ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
