addMultiOption method Null safety

void addMultiOption(
  1. String name,
  2. {String? abbr,
  3. String? help,
  4. String? valueHelp,
  5. Iterable<String>? allowed,
  6. Map<String, String>? allowedHelp,
  7. Iterable<String>? defaultsTo,
  8. void callback(
    1. List<String>
  9. bool splitCommas = true,
  10. bool hide = false,
  11. List<String> aliases = const []}

Defines an option that takes multiple values.

The abbr argument is a single-character string that can be used as a shorthand for this option. For example, abbr: "a" will allow the user to pass -a value or -avalue.

The help argument is used by usage to describe this option.

The valueHelp argument is used by usage as a name for the value this argument takes. For example, valueHelp: "FOO" will include --option=<FOO> rather than just --option in the usage string.

The allowed argument is a list of valid values for this argument. If it's non-null and the user passes a value that's not included in the list, parse will throw a FormatException. The allowed values will also be included in usage.

The allowedHelp argument is a map from values in allowed to documentation for those values that will be included in usage.

The defaultsTo argument indicates the values this option will have if the user doesn't explicitly pass it in (or [] by default).

The callback argument is invoked with the option's value when the option is parsed. Note that this makes argument parsing order-dependent in ways that are often surprising, and its use is discouraged in favor of reading values from the ArgResults.

If splitCommas is true (the default), multiple options may be passed by writing --option a,b in addition to --option a --option b.

If hide is true, this option won't be included in usage.

If aliases is provided, these are used as aliases for name. These aliases will not appear as keys in the options map.

Throws an ArgumentError if:

  • There is already an option with name name.
  • There is already an option using abbreviation abbr.


void addMultiOption(String name,
    {String? abbr,
    String? help,
    String? valueHelp,
    Iterable<String>? allowed,
    Map<String, String>? allowedHelp,
    Iterable<String>? defaultsTo,
    void Function(List<String>)? callback,
    bool splitCommas = true,
    bool hide = false,
    List<String> aliases = const []}) {
      defaultsTo?.toList() ?? <String>[],
      callback == null ? null : (value) => callback(value as List<String>),
      splitCommas: splitCommas,
      hide: hide,
      aliases: aliases);