R help - Feb 2010 - NextMethod() example from S Programming by Venables and Ripley (page 78)

S Programming by Venables and Ripley (page 78) has the example listed
at the end of this email. However, I get the following error when I
try the example. I don't understand the descriptions of NextMethod on
its help page. Could somebody let me know how to fix the error of this
example?
> test(x)
c1
c2
Error in NextMethod() : no method to invoke
Calls: test -> test.c1 -> NextMethod -> test.c2 -> NextMethod
Execution halted

####
test=function(x) UseMethod('test')

test.c1=function(x) {
  cat('c1\n')
  NextMethod()
  x
}

test.c2=function(x) {
  cat('c2\n')
  NextMethod()
  x
}

test.c3=function(x) {
  cat('c3\n')
  x
}

x=1
class(x)=c('c1','c2')
test(x)

blue sky <bluesky315 <at> gmail.com> writes:
> S Programming by Venables and Ripley (page 78) has the example listed
> at the end of this email. However, I get the following error when I
> try the example. I don't understand the descriptions of NextMethod on
> its help page. Could somebody let me know how to fix the error of this
> example?
> > test(x)
> c1
> c2
> Error in NextMethod() : no method to invoke
> Calls: test -> test.c1 -> NextMethod -> test.c2 -> NextMethod
> Execution halted
> 
> ####
> test=function(x) UseMethod('test')
> 
> test.c1=function(x) {
>   cat('c1\n')
>   NextMethod()
>   x
> }
> 
> test.c2=function(x) {
>   cat('c2\n')
>   NextMethod()
>   x
> }
> 
> test.c3=function(x) {
>   cat('c3\n')
>   x
> }
> 
> x=1
> class(x)=c('c1','c2')
> test(x)
It works fine for me if you add a default method,
which I think is what it is looking for. 

test.default <- function(x){
cat("default")
x
}

 test(x)
c1
c2
default[1] 1
attr(,"class")
[1] "c1" "c2"



-- 
Ken Knoblauch
Inserm U846
Stem-cell and Brain Research Institute
Department of Integrative Neurosciences
18 avenue du Doyen L?pine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
fax: +33 (0)4 72 91 34 61
portable: +33 (0)6 84 10 64 10
http://www.sbri.fr/members/kenneth-knoblauch.html