| formals {base} | R Documentation |
Access to and Manipulation of the Formal Arguments
Description
Get or set the formal arguments of a function.
Usage
formals(fun = sys.function(sys.parent()))
formals(fun, envir = parent.frame()) <- value
Arguments
fun |
a function object, or see Details. |
envir |
environment in which the function should be defined. |
value |
a list of R expressions. |
Details
For the first form, fun can be a character string
naming the function to be manipulated, which is searched for from the
parent environment.
If it is not specified, the function calling formals is used.
Value
formals returns the formal argument list of the function
specified.
The assignment form sets the formals of a function to the list on the right hand side.
See Also
args for a “human-readable” version,
alist,
body,
function.
Examples
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