scribeArg-class {scribe}

scribe argument

Description

ReferenceClass object for managing arguments

Details

The scribeArg class sets specifications and controls for how command line arguments are to be parsed. These are meant to be used in conjunction with scribeCommandArgs and specifically with the Rscript utility. However, a use can define their own scribeArg separately.

Fields

aliases

⁠[character]⁠
A vector to denote the argument's name

action

⁠[character]⁠
An action for resolving the argument (see default for note on using another scribeArg object)

default

⁠[ANY]⁠
A default value. This can be another scribeArg object. When that is the case, the default value and action are pass through from the other scribeArg object.

convert

⁠[ANY]⁠
Passed to the to argument in value_convert()

n

⁠[integer]⁠
The length of the values

info

⁠[character]⁠
Additional information about the argument when printed

options

⁠[list]⁠
A named list of options (see Options)

positional

⁠[logical]⁠
Indicator if the argument is positional (i.e., not preceded by a - or ⁠--⁠ command line argument)

resolved

⁠[logical]⁠
Has the object been resolved

value

⁠[ANY]⁠
The resolve value

stop

⁠[character]⁠
"none", "hard", or "soft"

execute

⁠[function]⁠
(For advanced use). A function to be evaluated along with the arg. The function can have no parameters, a single parameter for the scribeArg object, or accept the scribeArg object as its first argument, and the scribeCommandArgs object as its second. Both objects will be passed by position

Methods

get_action()

Retrieve action

get_aliases()

Retrieve aliases

get_default()

Retrieve the default value

get_help()

Retrieve help information as a character vector

get_name(clean = TRUE)

Retrieve names

clean

When TRUE removes -s from text

get_value()

Retrieve the resolved value

help()

Print out formatted help information

initialize( aliases = "", action = arg_actions(), default = NULL, convert = scribe_convert(), n = NA_integer_, info = NA_character_, options = list(), stop = c("none", "hard", "soft"), execute = invisible )

Initialize the scribeArg object

See fields for parameter information.

is_resolved()

Check if object has been resolved

Options

Several available options

action="list"

choices

An explicit set of values that argument must be. If the value parsed is not one of these, an error will occur.

action="flag"

no

When TRUE included appends --no to aliases to invert results
Example:
With the argument new_arg("--test", options = list(no = TRUE)), passing command arguments --test would set this to TRUE and --no-test explicitly set to FALSE.

See Also

Other scribe: command_args(), new_arg(), scribeCommandArgs-class

Examples

# new_arg() is recommended over direct use of scribeArg$new()

# arguments with `--` indicators
new_arg("--verbose", action = "flag")
new_arg(c("-f", "--force"), action = "flag")
new_arg("--values", action = "list")

# positional
new_arg("verbose", action = "flag")
new_arg("value", action = "list", n = 1)

# special `...` action which absorbs left-over arguments
new_arg("values", action = "dots", info = "list of values")
new_arg("...", info = "list of values") # defaults when alias is "..."