match.call returns a call in which all of the specified arguments are
specified by their full names.
match.call(definition = sys.function(sys.parent()), call = sys.call(sys.parent()), expand.dots = TRUE, envir = parent.frame(2L))match.call is called. See details.definition, as generated by call....
in the call be included or left as a ... argument?... in call
are retrieved, if any.call.
match.call does not support
primitive functions (where argument matching is normally
positional). match.call is most commonly used in two circumstances:
call of
the list they return. Here the default expand.dots = TRUE
is appropriate.
model.frame. Here the common idiom is that
expand.dots = FALSE is used, and the ... element
of the matched call is removed. An alternative is to
explicitly select the arguments to be passed on, as is done in
lm.
Calling match.call outside a function without specifying
definition is an error.
sys.call() is similar, but does not expand the
argument names;
call, pmatch, match.arg,
match.fun.
match.call(get, call("get", "abc", i = FALSE, p = 3))
## -> get(x = "abc", pos = 3, inherits = FALSE)
fun <- function(x, lower = 0, upper = 1) {
structure((x - lower) / (upper - lower), CALL = match.call())
}
fun(4 * atan(1), u = pi)
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