A function to create an instance of a parser object

This function is used to create an instance of a parser object which when combined with the parse_args(), make_option(), and add_option() methods is very useful for parsing options from the command line.

Usage

OptionParser(
  usage = "usage: %prog [options]",
  option_list = list(),
  add_help_option = TRUE,
  prog = NULL,
  description = "",
  epilogue = "",
  formatter = IndentedHelpFormatter
)

Arguments

usage

The program usage message that will printed out if parse_args() finds a help option, \%prog is substituted with the value of the prog argument.

option_list

A list of of OptionParserOption instances that will define how parse_args() reacts to command line options. OptionParserOption instances are usually created by make_option() and can also be added to an existing OptionParser instance via the add_option() function.

add_help_option

Whether a standard help option should be automatically added to the OptionParser instance.

prog

Program name to be substituted for \%prog in the usage message (including description and epilogue if present), the default is to use the actual Rscript file name if called by an Rscript file and otherwise keep \%prog.

description

Additional text for print_help() to print out between usage statement and options statement

epilogue

Additional text for print_help() to print out after the options statement

formatter

A function that formats usage text. The function should take only one argument (an OptionParser() object). Default is IndentedHelpFormatter(). The other builtin formatter provided by this package is TitledHelpFormatter().

Value

An instance of the OptionParser class.

References

Python's optparse library, which inspired this package, is described here: https://docs.python.org/3/library/optparse.html

See also

parse_args() make_option() add_option()