R-alpha: R-0.50-a3(+) Method despatching bug ?

Thomas Lumley Thomas Lumley <thomas@biostat.washington.edu>
Wed, 20 Aug 1997 10:34:35 -0700 (PDT)

On Wed, 20 Aug 1997, Martin Maechler wrote:

> It is very wierd...  Can some of you confirm the following behavior ?
> It is a new bug (feature ?)  which was not yet in 0.49 ...

I'm not sure that you can expect NextMethod to work if you fiddle with the
class list...

However, there is still something wrong with method dispatching, since
print.noquote <- function (obj, ...)  NextMethod(quote = FALSE,...)
doesn't work either.  The error occurs when R tries for some reason to
make a recursive call to print.noquote.

Using debug() also shows the interesting fact that
R> nq 
calls print() with its arguments evaluated
debugging in: print(structure(c("a", "b", "c", "d", "e", "f", "g", "h",
"j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", "u", "v", 
"w", "x", "y", "z"), class = "noquote"))
debugging in: print.noquote(structure(c("a", "b", "c", "d", "e", "f", "g", 
"h", "i", "j", "k", "l", "m", "n", "o", "p", "q", "r", "s", "t", 
"u", "v", "w", "x", "y", "z"), class = "noquote"))
Error: couldn't find function "print.noquote"
R> print(nq)
debugging in: print(nq)
debugging in: print.noquote(nq)
 [1] a b c d e f g h i j k l m n o p q r s t u v w x y z
[1] noquote
exiting from: print.noquote(nq)
exiting from: print(nq)
doesn't evaluate the argument first.

Thomas Lumley
Biostatistics		: "Never attribute to malice what  :
Uni of Washington	:  can be adequately explained by  :
Box 357232		:  incompetence" - Hanlon's Razor  :
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