This turned up in the same context as #743, i.e. writing data.restore.
Two bugs, I think:
The way arguments with no defaults are stored appears to be as a
zero-length name:
> test <- function(x) 1
> as.list(test)$x
> mode(as.list(test)$x)
[1] "name"
> as.character(as.list(test)$x)
[1] ""
However, I'm not allowed to create one of those:
> as.name("")
Error in as.name("") : attempt to use zero-length variable name
If I'm sneaky, I can create one, but I can't do anything with it:
> badvar <- as.list(test)$x
> badvar
Error: Argument "badvar" is missing, with no default
> junk <- badvar
Error: Argument "badvar" is missing, with no default
> junk
Error: Object "junk" not found
For now, the workaround I'm using when building up functions like
"test" above is to create them as
function(x = stop("argument x is missing")) 1
but this is ugly.
Duncan Murdoch
Version:
platform = Windows
arch = x86
os = Win32
system = x86, Win32
status =
major = 1
minor = 1.1
year = 2000
month = August
day = 15
language = R
Windows 9x 4.0 (build 1111) B
Search Path:
.GlobalEnv, Autoloads, package:base
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