Message-ID: <CAOKDuOjM0HZ+-e++P7J951DpWk4yn1uPO+e+j_N-xLHJmL_Oaw@mail.gmail.com>
Date: 2018-05-03T14:52:19Z
From: Mark van der Loo
Subject: length of `...`
In-Reply-To: <d0b68216-4922-2249-e5e6-1589345dc6d7@kogentum.hu>
This question is better aimed at the r-help mailinglist as it is not about
developing R itself.
having said that,
I can only gues why you want to do this, but why not do something like this:
f <- function(...){
L <- list(...)
len <- length()
# you can stll pass the ... as follows:
do.call(someotherfunction, L)
}
-Mark
Op do 3 mei 2018 om 16:29 schreef D?nes T?th <toth.denes at kogentum.hu>:
> Hi,
>
>
> In some cases the number of arguments passed as ... must be determined
> inside a function, without evaluating the arguments themselves. I use
> the following construct:
>
> dotlength <- function(...) length(substitute(expression(...))) - 1L
>
> # Usage (returns 3):
> dotlength(1, 4, something = undefined)
>
> How can I define a method for length() which could be called directly on
> `...`? Or is it an intention to extend the base length() function to
> accept ellipses?
>
>
> Regards,
> Denes
>
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> https://stat.ethz.ch/mailman/listinfo/r-devel
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