[R] Additional arguments in S3 method produces a warning

[Philippe Grosjean]

Hello,
I just notice this:
 > x <- c(1:4,0:5, 4, 11)
 > library(pastecs)
Loading required package: boot
 > tp <- turnpoints(x)
 > extract(tp, no.tp = FALSE, peak = TRUE, pit = FALSE)
  [1] FALSE FALSE FALSE  TRUE FALSE FALSE FALSE FALSE FALSE  TRUE FALSE 
FALSE
Warning message:
arguments after the first two are ignored in: UseMethod("extract", e, n, 
...)
 > extract(tp)
  [1]  0  0  0  1 -1  0  0  0  0  1 -1  0
Warning message:
arguments after the first two are ignored in: UseMethod("extract", e, n, 
...)

My extract.turnpoints() function produces warnings. I can easily spot 
the origin of this warning:

 > extract
function (e, n, ...)
UseMethod("extract", e, n, ...)
 > extract.turnpoints
function (e, n, no.tp = 0, peak = 1, pit = -1, ...)
{
     if (missing(n))
         n <- length(e)
     res <- rep(no.tp, length.out = e$n)
     res[e$pos[e$peaks]] <- peak
     res[e$pos[e$pits]] <- pit
     if (n < length(res) & n > 0)
         res <- res[1:n]
     res
}

This is because my extract.turnpoints() method defines more arguments 
than 'e' and 'n' in the generic function. However,

1) I though that the '...' argument in S3 generic function was there to 
allow defining/passing additional arguments in/to S3 methods. Is this 
correct? If yes, why the warning?

2) Despite the warning says arguments after the first two are ignored, 
this appears not to be the case: in this example, 'no.tp', 'peak' and 
'pit' arguments are taken into account, as you can see (different 
behaviour if you give other values to them).

I am a little bit lost. Could someone help me, please.

Best,

Philippe Grosjean


-- 
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  ) ) ) ) )
( ( ( ( (    Prof. Philippe Grosjean
  ) ) ) ) )
( ( ( ( (    Numerical Ecology of Aquatic Systems
  ) ) ) ) )   Mons-Hainaut University, Pentagone (3D08)
( ( ( ( (    Academie Universitaire Wallonie-Bruxelles
  ) ) ) ) )   8, av du Champ de Mars, 7000 Mons, Belgium
( ( ( ( (
  ) ) ) ) )   phone: + 32.65.37.34.97, fax: + 32.65.37.30.54
( ( ( ( (    email: Philippe.Grosjean at umh.ac.be
  ) ) ) ) )
( ( ( ( (    web:   http://www.umh.ac.be/~econum
  ) ) ) ) )          http://www.sciviews.org
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