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

[Package base version 2.1.0 Index]