do.call: Execute a Function Call
In robertzk/monadicbase: The R Base Package

Description Usage Arguments Details Value Warning References See Also Examples

do.call constructs and executes a function call from a name or a function and a list of arguments to be passed to it.

1	do.call(what, args, quote = FALSE, envir = parent.frame())

`what`	either a function or a non-empty character string naming the function to be called.
`args`	a list of arguments to the function call. The `names` attribute of `args` gives the argument names.
`quote`	a logical value indicating whether to quote the arguments.
`envir`	an environment within which to evaluate the call. This will be most useful if `what` is a character string and the arguments are symbols or quoted expressions.

If quote is FALSE, the default, then the arguments are evaluated (in the calling environment, not in envir). If quote is TRUE then each argument is quoted (see quote) so that the effect of argument evaluation is to remove the quotes – leaving the original arguments unevaluated when the call is constructed.

The behavior of some functions, such as substitute, will not be the same for functions evaluated using do.call as if they were evaluated from the interpreter. The precise semantics are currently undefined and subject to change.

The result of the (evaluated) function call.

This should not be used to attempt to evade restrictions on the use of .Internal and other non-API calls.

Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988) The New S Language. Wadsworth & Brooks/Cole.

call which creates an unevaluated call.

do.call("complex", list(imag = 1:3))

## if we already have a list (e.g., a data frame)
## we need c() to add further arguments
tmp <- expand.grid(letters[1:2], 1:3, c("+", "-"))
do.call("paste", c(tmp, sep = ""))

do.call(paste, list(as.name("A"), as.name("B")), quote = TRUE)

## examples of where objects will be found.
A <- 2
f <- function(x) print(x^2)
env <- new.env()
assign("A", 10, envir = env)
assign("f", f, envir = env)
f <- function(x) print(x)
f(A)                                      # 2
do.call("f", list(A))                     # 2
do.call("f", list(A), envir = env)        # 4
do.call(f, list(A), envir = env)          # 2
do.call("f", list(quote(A)), envir = env) # 100
do.call(f, list(quote(A)), envir = env)   # 10
do.call("f", list(as.name("A")), envir = env) # 100

eval(call("f", A))                      # 2
eval(call("f", quote(A)))               # 2
eval(call("f", A), envir = env)         # 4
eval(call("f", quote(A)), envir = env)  # 100