option {optional} | R Documentation |
Make a variable optional.
option
is an object wrapper which indicates
whether the object is valid or not.
option(arg)
arg |
The variable to make optional |
Note that option(option(i)) == option(i)
and option(none) == FALSE
Operators and print will have the same behavior with an optional than with its base type.
arg
as optional
none, opt_unwrap(), make_opt()
a <- option(5)
class(a)
## [1] "optional"
a == 5
## [1] TRUE
a
## [1] 5