Re: [Rd] Bug in new() or validObject() in methods package (PR#7922)
McGehee, Robert wrote: The bug might be here: is.null(expression()) [1] TRUE But is.null(expression(NULL)) [1] FALSE So it might look to the methods package like you're passing in a NULL value for @bar. I might argue that expression() should not be NULL (and only NULL is NULL) as I have had similar trouble trying to extend language objects to S4 classes, partially because length 0 name, call and expression objects are either not available, or in this case, handled poorly. I think you've spotted it. The internal code for is.null checks for NULL or a zero length expression, not just for NULL. Changing that so it only accepts NULL fixes this bug. This code has been in place since prehistoric times, so I'm going to tread pretty carefully here before I commit a change. Duncan Murdoch __ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
Re: [Rd] Bug in new() or validObject() in methods package (PR#7922)
[EMAIL PROTECTED] writes: Is it doing an extra eval or something? It looks like it: x - expression() x expression() eval(x) NULL x - quote(expression()) x expression() eval(x) expression() eval(eval(x)) NULL You do realize that the two expression() results are not identical: x - quote(expression()) class(x) [1] call x - expression() class(x) [1] expression Not that I can fathom what bearing that has on the real problem... -- O__ Peter Dalgaard Blegdamsvej 3 c/ /'_ --- Dept. of Biostatistics 2200 Cph. N (*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918 ~~ - ([EMAIL PROTECTED]) FAX: (+45) 35327907 __ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
RE: [Rd] Bug in new() or validObject() in methods package (PR#7922)
The bug might be here: is.null(expression()) [1] TRUE But is.null(expression(NULL)) [1] FALSE So it might look to the methods package like you're passing in a NULL value for @bar. I might argue that expression() should not be NULL (and only NULL is NULL) as I have had similar trouble trying to extend language objects to S4 classes, partially because length 0 name, call and expression objects are either not available, or in this case, handled poorly. Robert -Original Message- From: Duncan Murdoch [mailto:[EMAIL PROTECTED] Sent: Monday, June 06, 2005 4:58 PM To: Peter Dalgaard Cc: r-devel@stat.math.ethz.ch Subject: Re: [Rd] Bug in new() or validObject() in methods package (PR#7922) On 6/6/2005 4:55 PM, Peter Dalgaard wrote: [EMAIL PROTECTED] writes: Is it doing an extra eval or something? It looks like it: x - expression() x expression() eval(x) NULL x - quote(expression()) x expression() eval(x) expression() eval(eval(x)) NULL You do realize that the two expression() results are not identical: x - quote(expression()) class(x) [1] call x - expression() class(x) [1] expression Not that I can fathom what bearing that has on the real problem... I figured they weren't identical, given that they gave different results when eval'd, but I didn't know what the difference was exactly. Thanks! Duncan __ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel __ R-devel@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
