[R] nargs() inside "[.myclass"
Vadim Kutsyy
vkutsyy at yahoo.com
Mon Jun 26 23:48:49 CEST 2000
> > "[.myclass"<-function(x,...)
> > {n<-nargs();print(n-1);m<-match.call();print(m)}
> > x[]
> [1] 1
> [.myclass(x = x, )
> > x[1]
> [1] 1
> [.myclass(x = x, 1)
> > x[1,2]
> [1] 2
> [.myclass(x = x, 1, 2)
>
> Doesn't look quite right... The problem sees to be that in the x[]
> case one passes two arguments of which one is missing (note that f(x)
> and f(x,) is not quite the same thing).
exactly, but if you don't pass anything at all, you can not even test if
something is missing, ie:
> "[.myclass"<-function(x,...) {n<-nargs();print(n-1);print(list(...))}
> x<-c(1,2,3)
> class(x)<-"myclass"
> x[1]
[1] 1
[[1]]
[1] 1
> x[]
[1] 1
Error in print(list(...)) : Argument is missing, with no default
As a result, I can not figure out way to see if it was pass as x[] or x[1].
It is possible to differentiate x[1,] vs x[1,2].
Any idea, how to get around it?
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