Built-in callbacks for option definitions {defineOptions}

Built-in callbacks for option definitions

Description

define_option function takes an callback argument. The following functions return built-in callbacks for the callback argument.

Usage

opt_optional_input_required( input_when_omitted )
opt_optional_input_disallowed( input_when_specified, input_when_omitted)
opt_required_input_required()

Arguments

input_when_omitted

character

input_when_specified

character

Details

opt_optional_input_required() function returns a callback that is used to define that the option is optional but when the option is specified its input value is required to be specified. opt_optional_input_disallowed() function returns a callback that is used to define that the option is optional and input value should not be specified. This kind of option is called a flag. opt_required_input_required() function returns a callback that is used to define that the option is required and its value is also required.

Value

Function object

See Also

define_option ParserDef-class defineOptions-package

Examples

callback = opt_optional_input_required( input_when_omitted = "70,180" )
callback = opt_optional_input_disallowed( input_when_specified = "TRUE",
                                          input_when_omitted = "FALSE" )
callback = opt_required_input_required()