R devel - Jan 2006 - defining a print method

In the following session we define an xx class and a print method
for it.  If I invoke it with print then it prints as expected but if
we just type xx at the R prompt then we get nothing back.  How
do we define the print method so that it works in the latter
case too?
> xx <- structure("abc", class = "xx")
> print.xx <- function(x, ...) shQuote(x)
> print(xx) # ok
[1] "\"abc\""
> xx # no output ????
>
> sessionInfo()
R version 2.2.1, 2005-12-20, i386-pc-mingw32

attached base packages:
[1] "methods"   "stats"     "graphics" 
"grDevices" "utils"     "datasets"
[7] "base"
>

On 1/4/06, Gabor Grothendieck <ggrothendieck at gmail.com>
wrote:
> In the following session we define an xx class and a print method
> for it.  If I invoke it with print then it prints as expected but if
> we just type xx at the R prompt then we get nothing back.  How
> do we define the print method so that it works in the latter
> case too?
>
> > xx <- structure("abc", class = "xx")
> > print.xx <- function(x, ...) shQuote(x)
shQuote doesn't print anything, you probably want

print.xx <- function(x, ...) print(shQuote(x))

-Deepayan
> > print(xx) # ok
> [1] "\"abc\""
> > xx # no output ????
> >
> > sessionInfo()
> R version 2.2.1, 2005-12-20, i386-pc-mingw32
>
> attached base packages:
> [1] "methods"   "stats"     "graphics" 
"grDevices" "utils"     "datasets"
> [7] "base"