[R] understanding as.list(substitute(...()))

[Bert Gunter]

You need to understand what substitute() does -- see ?substitute and/or a
tutorial on "R computing on the language" or similar.

Here is a simple example that may clarify:

> dots <- function(...) as.list(substitute(...()))
> dots(log(foo))
[[1]]
log(foo)  ## a call, a language object

> dots2 <- function(...) as.list(...)
> dots2(log(foo))
Error in as.list(...) : object 'foo' not found
## substitute() does not evaluate its argument; as.list() does

Cheers,
Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Mon, Oct 5, 2020 at 1:37 PM Tim Taylor <tim.taylor using hiddenelephants.co.uk>
wrote:

> Could someone explain what is happening with the ...() of the
> following function:
>
> dots <- function(...) as.list(substitute(...()))
>
> I understand what I'm getting as a result but not why.   ?dots and
> ?substitute leave me none the wiser.
>
> regards
> Tim
>
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