optional (version 2.0.1)

option: option

Description

Make a variable optional.

option is an object wrapper which indicates whether the object is valid or not.

Usage

option(arg)

Arguments

arg

The variable to make optional

Value

arg as optional

Details

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.

See Also

none, opt_unwrap(), make_opt()

Examples

# NOT RUN {
a <- option(5)
class(a)
## [1] "optional"

a == 5
## [1] TRUE

a
## [1] 5
# }