[Rd] Bug with ..0

Duncan Murdoch murdoch.duncan at gmail.com
Sun May 30 21:40:29 CEST 2010


On 30/05/2010 3:13 PM, Gabor Grothendieck wrote:
> This function call returns 3 but should return 32.  ..0 has no special
> significance in R as far I know yet it seems to be acting as if it
> were ..1 .  Comments?
>   

Actually, ..0 is a reserved symbol.  (This is just barely documented in 
the R Language Defn, with more detail in R Internals.)  It stands for 
the "zeroth element of ..."  That definition makes no sense (indexing of 
... starts at 1), so we should probably generate an error when you use 
it, and perhaps when you try to redefine it by using it as an argument.  
But this is really a case of you doing something you shouldn't, and the 
error handling not slapping you on the wrist.

Duncan Murdoch
>   
>> ff <- function(..0, ...) ..0
>> ff(32, 3)
>>     
> [1] 3
>
>   
>> R.version.string
>>     
> [1] "R version 2.11.0 Patched (2010-04-26 r51822)"
>   
>> win.version()
>>     
> [1] "Windows Vista (build 6002) Service Pack 2"
>
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