R devel - Apr 2010 - callNextMethod() and NAMESPACE

Hello there,

I define a accessor method for one of my classes, i.e.

setMethod(f = "[",
   signature = "NG_data",
     definition = function(x,i,j,drop){
        if(all(is.na(match(j,x at shortnames)) == FALSE)){
          return(x[,match(j,x at shortnames)])                           }else{
          callNextMethod()
        }
     }
)

where the class "NG_data" inherits from the "data.frame"
class. Hence I
added the line

exportMethods("[")

to my NAMESPACE file. After package building, installing and loading, I 
try to use this accessor method

myObject[,1]

but I get the error message:

Error in callNextMethod() : bad object found as method (class
"function")

Interestingly, if I then execute the setMethod(f = "["...  in the 
command prompt

myObject[,1]

works. Does anybody has a clue what could go wrong?


Adrian Waddell

It could be that you define the below in two different source files
and you are only updating the first and it is overwritten by the
second which you never edit? /Henrik

On Thu, Apr 15, 2010 at 4:21 PM, Adrian Waddell <adrian at waddell.ch>
wrote:
> Hello there,
>
> I define a accessor method for one of my classes, i.e.
>
> setMethod(f = "[",
> ?signature = "NG_data",
> ? ?definition = function(x,i,j,drop){
> ? ? ? if(all(is.na(match(j,x at shortnames)) == FALSE)){
> ? ? ? ? return(x[,match(j,x at shortnames)]) ? ? ? ? ? ? ? ? ? ? ? ? ?
}else{
> ? ? ? ? callNextMethod()
> ? ? ? }
> ? ?}
> )
>
> where the class "NG_data" inherits from the
"data.frame" class. Hence I
> added the line
>
> exportMethods("[")
>
> to my NAMESPACE file. After package building, installing and loading, I try
> to use this accessor method
>
> myObject[,1]
>
> but I get the error message:
>
> Error in callNextMethod() : bad object found as method (class
"function")
>
> Interestingly, if I then execute the setMethod(f = "["... ?in the
command
> prompt
>
> myObject[,1]
>
> works. Does anybody has a clue what could go wrong?
>
>
> Adrian Waddell
>
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