[R] no partial matching of argument names after dots argument - why?

[Mark Heckmann]

I noticed that the argument names after the dots argument are not partially matched.

foo <- function(one, two, ...){
  one + two
}
> foo(o=1, t=2)
[1] 3

foo <- function(one, ..., two){
   one + two
}   

> foo(o=1, t=2) 
Fehler in one + two : 'two' fehlt


Can someone explain me the reason for this behavior?

THX
Mark 

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Mark Heckmann
Blog: www.markheckmann.de
R-Blog: http://ryouready.wordpress.com