[Rd] Capturing argument values
ross at biostat.ucsf.edu
Sun Dec 31 02:20:17 CET 2006
I would like to preserve the values of all the arguments to a function
in a results object.
foo <- function(a, b=1) ....
match.call() looks promising, but it records that a is x, while I want
the value of x (in the calling frame). Also, if the invocation is
foo(x), then match.call doesn't record that b is 1.
So I tried this (inside the function definition):
myargs <- lapply(names(formals()),
That's pretty close. However, my function has an optional argument in
bar <- function(x, testing) ...
where code in the body is
if (! missing(testing)) do stuff
When the eval in the previous lapply runs for a function call in which
testing is not supplied, I get
Error in eval(expr, envir, enclos) : argument "testing" is missing,
with no default
exposing a weakness in both my implementation and problem specification.
I think I could simply screen "testing" out of the formals and be
happy, but are there better ways of handling this situation?
I realize I could capture the function's entire local frame, but that
has quite a bit of stuff I don't want in it. I suspect some of the
items in it might be promises, and so would not have the values I
needed as well. (Also the frame could later change, though I guess I
could convert it to a list to avoid that problem.)
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