[Rd] obscure error with subsetting as.list() of a function then assigning that a (PR#9500)

peter-m.schumacher at db.com peter-m.schumacher at db.com
Thu Feb 8 19:08:25 CET 2007

Hello. I was writing some code that computes on the language and came across
this. I can work around it, but thought you might like to know about it.

> f <- function(x) { NULL }
> a <- as.list(f)[[1]]
> a # ie print(a)
Error: argument "a" is missing, with no default

Note it says *argument* "a", which is strange. In fact, and unsurprisingly, the bug lies
with the object itself, not with print():

> typeof(a)
Error in typeof(a) : argument "a" is missing, with no default
> deparse(a)
Error in deparse(a) : argument "a" is missing, with no default

However, this does work:
> as.list(f)[[1]]

It prints nothing, which is correct, and there is no error. So it seems the bug lies with
assigning a name to as.list(f)[[1]] as above, then trying to work with that new object.

Peter-M.Schumacher at db.com

--please do not edit the information below--

 platform = i386-pc-mingw32
 arch = i386
 os = mingw32
 system = i386, mingw32
 status =
 major = 2
 minor = 4.1
 year = 2006
 month = 12
 day = 18
 svn rev = 40228
 language = R
 version.string = R version 2.4.1 (2006-12-18)

Windows XP Professional (build 2600) Service Pack 2.0

LC_COLLATE=English_United Kingdom.1252;LC_CTYPE=English_United Kingdom.1252;LC_MONETARY=English_United Kingdom.1252;LC_NUMERIC=C;LC_TIME=English_United Kingdom.1252

Search Path:
 .GlobalEnv, file:c:/schupl/R/myRLib/.RData, package:stats, package:graphics, package:grDevices, package:utils, package:datasets, package:methods, Autoloads, package:base

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