formals {base} | R Documentation |
Get or set the formal arguments of a function.
formals(fun = sys.function(sys.parent())) formals(fun, envir = environment(fun)) <- value
fun |
a function object, or see ‘Details’. |
envir |
environment in which the function should be defined. |
value |
a list (or pairlist) of R expressions. |
For the first form, fun
can also be a character string naming
the function to be manipulated, which is searched for from the parent
frame. If it is not specified, the function calling formals
is
used.
Only closures have formals, not primitive functions.
formals
returns the formal argument list of the function
specified, as a pairlist
, or NULL
for a
non-function or primitive.
The replacement form sets the formals of a function to the list/pairlist on the right hand side, and (potentially) resets the environment of the function.
args
for a human-readable version,
alist
,
body
,
function
.
require(stats); require(graphics) length(formals(lm)) # the number of formal arguments names(formals(boxplot)) # formal arguments names f <- function(x) a+b formals(f) <- alist(a = , b = 3) # function(a, b = 3) a+b f(2) # result = 5