Note that substitute(...()) and substitute(someFunc(...))[-1] give slightly different results, the former a pairlist and the latter a call. > str((function(...)substitute(...()))(stop(1),stop(2),stop(3))) Dotted pair list of 3 $ : language stop(1) $ : language stop(2) $ : language stop(3) > str((function(...)substitute(someFunc(...))[-1])(stop(1),stop(2),stop(3))) language stop(1)(stop(2), stop(3))
The ...() idiom has been around for a long time, but more recently (slightly after R-3.4.0?) the ...elt(n) and ...length() functions were introduced so you don't have to use it much. I don't see a ...names() function that would give the names of the ... arguments - names(substitute(...())). Bill Dunlap TIBCO Software wdunlap tibco.com On Thu, Mar 12, 2020 at 2:09 AM Dénes Tóth <toth.de...@kogentum.hu> wrote: > Dear R Core Team, > > I learnt approx. two years ago in this mailing list that one can use the > following "trick" to get a (dotted pair)list of the ellipsis arguments > inside a function: > > `substitute(...())` > > Now my problem is that I can not find any occurrence of this call within > the R source - the most frequent solution there is > `substitute(list(...))[-1L] ` > > I would like to know if: > 1) substitute(...()) is a trick or a feature in the language; > 2) it will be supported in the future; > 3) when (in which R version) it was introduced. > > A hint on where to look for the machinery in the R source would be also > appreciated. > > Regards, > Denes > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
