call                  package:base                  R Documentation

Function Calls

Description:

     Create or test for objects of mode `"call"'.

Usage:

     call(name, ...)
     is.call(x)
     as.call(x)

Arguments:

    name: a character string naming the function to be called.

     ...: arguments to be part of the call.

       x: an arbitrary R object.

Value:

     `call' returns an unevaluated function call, that is, an
     unevaluated expression which consists of the named function
     applied to the given arguments (`name' must be a quoted string
     which gives the name of a function to be called).

     `is.call' is used to determine whether `x' is a call (i.e., of
     mode `"call"').

     It is not possible to coerce objects to mode call (objects either
     are calls or they are not calls).  `as.call' returns its argument
     if it is a call and otherwise terminates with an error message.

See Also:

     `do.call' for calling a function by name and argument list;
     `Recall' for recursive calling of functions; further
     `is.language', `expression', `function'.

Examples:

     is.call(call) #-> FALSE: Functions are NOT calls

     # set up a function call to round with argument 10.5
     cl <- call("round", 10.5)
     is.call(cl)# TRUE
     cl
     # such a call can also be evaluated.
     eval(cl)# [1] 10

