existsFunction(name, generic=TRUE, where, frame=NULL)
where is supplied, it can either be a number or an object defining
a database.
A number specifies the corresponding element of the search list. For example,
where=2 checks the second database for the existence of the
specified function and returns TRUE if the function is found.
Otherwise,
where is interpreted as a database of any type.
This database is accessed, but it is not put on the search list.
where and
frame.
Returns 'TRUE' if there is a function object with this name. If 'generic == FALSE', then ignore generic functions. This function is useful if you want to check the existence of a function before sourcing a function of the same name. See the example below.
existsFunction("get", where="main")
# returns TRUE
## Contents of the file my.fun.q
# my.fun <- function(x) {
# x * 2
# }
#
## check to see if my.fun already exists.
## if not, source the function from the
## file, and then call the function.
# if !existsFunction("my.fun") {
# source("my.fun.q")
# }
# my.fun(22)