Use globally specified defaults, if set, in place of formally specified default argument values. Allows user to specify function defaults different than formally supplied values, e.g. to change poorly performing defaults, or satisfy a different preference.
setDefaults(name, ...)
unsetDefaults(name, confirm = TRUE)
getDefaults(name = NULL, arg = NULL)
importDefaults(calling.fun)
None. Used for it's side effect of setting a list of default arguments by function.
None. Used for it's side effect of unsetting default arguments by function.
A named list of defaults and associated values, similar to
formals, but only returning values set by setDefaults
for the name function. Calling getDefaults() (without
arguments) returns in a character vector of all functions currently
having defaults set (by setDefaults).
This does not imply that the returned function names are able
to accept defaults (via importDefaults), rather that they have
been set to store user defaults. All values can also be viewed with a
call to getOption(name_of_function.Default).
None. Used for its side-effect of loading all non-NULL user-
specified default values into the current function's environment,
effectively changing the default values passed in the parent function
call. Like formally defined defaults in the function definition,
default values set by importDefaults take lower precedence
than arguments specified by the user in the function call.
name of function, quoted or unquoted (see Details)
name=value default pairs
prompt before unsetting defaults
values to retrieve
name of function to act upon
Jeffrey A. Ryan
Provides a wrapper to R options that allows the user to
specify any name=value pair for a function's formal arguments.
Only formal name=value pairs specified will be updated.
Values do not have to be respecified in subsequent calls to
setDefaults, so it is possible to add new defaults for each
function one at a time, without having to retype all previous values.
Assigning NULL to any argument will remove the argument from
the defaults list.
name can be an unquoted, bare symbol only at the top-level. It
must be a quoted character string if you call setDefaults inside
a function.
Removes name=value pairs from the defaults list.
Provides access to the stored user defaults. Single arguments need not be quoted, multiple arguments must be in a character vector.
A call to importDefaults should be placed on the first line
in the body of the function. It checks the user's environment for
globally specified default values for the called function. These
defaults can be specified by the user with a call to
setDefaults, and will override any default formal
parameters, in effect replacing the original defaults with user
supplied values instead. Any user-specified values in the parent
function (that is, the function containing importDefaults)
will override the values set in the global default environment.
my.fun <- function(x=3)
{
importDefaults('my.fun')
x^2
}
my.fun() # returns 9
setDefaults(my.fun, x=10)
my.fun() # returns 100
my.fun(x=4) # returns 16
getDefaults(my.fun)
formals(my.fun)
unsetDefaults(my.fun, confirm=FALSE)
getDefaults(my.fun)
my.fun() # returns 9
Run the code above in your browser using DataLab