Class to hold information about command-line options
short_flagString of the desired short flag comprised of the “-” followed by a letter.
long_flagString of the desired long flag comprised of “--” followed by a letter and then a sequence of alphanumeric characters.
actionA character string that describes the action optparse
should take when it encounters an option, either “store”,
“store_true”, or “store_false”. The default is “store”
which signifies that optparse should store the specified following
value if the option is found on the command string. “store_true”
stores TRUE if the option is found and “store_false” stores
FALSE if the option is found.
typeA character string that describes specifies which data type
should be stored, either “logical”, “integer”, “double”,
“complex”, or “character”. Default is “logical” if
action %in% c("store_true", store_false), typeof(default) if
action == "store" and default is not NULL and
“character” if action == "store" and default is NULL.
“numeric” will be converted to “double”.
destA character string that specifies what field in the list returned
by parse_args should optparse store option values. Default is
derived from the long flag in opt_str.
defaultThe default value optparse should use if it does not
find the option on the command line.
helpA character string describing the option to be used by
print_help in generating a usage message. %default will be
substituted by the value of default.
metavarA character string that stands in for the option argument when
printing help text. Default is the value of dest.
callbackA function that executes after the each option value is fully parsed
callback_argsAdditional arguments that pass to the callback function.
make_option