addCommandLine method

ConfigurationBuilder addCommandLine(Iterable<String> args, [ LinkedHashMap<String, String>? switchMappings ])

Adds a CommandLineConfigurationProvider ConfigurationProvider that reads configuration values from the command line.

The values passed on the command line, in the args string array, should be a set of keys prefixed with two dashes ("--") and then values, separate by either the equals sign ("=") or a space (" ").

A forward slash ("/") can be used as an alternative prefix, with either equals or space, and when using an equals sign the prefix can be left out altogether.

There are five basic alternative formats for arguments: key1=value1 --key2=value2 /key3=value3 --key4 value4 /key5 value5.

A simple console application that has five values.

// dart example.dart key1=value1 --key2=value2 /key3=value3 --key4 value4 /key5 value5
void main(List<String> args) {
  final builder = ConfigurationBuilder()
  ..addCommandLine(args);

  final config = builder.build();
  print('Key1: \'${config["Key1"]}\'');
  print('Key2: \'${config["Key2"]}\'');
  print('Key3: \'${config["Key3"]}\'');
  print('Key4: \'${config["Key4"]}\'');
  print('Key5: \'${config["Key5"]}\'');
}

The switchMappings allows additional formats for alternative short and alias keys to be used from the command line. Also see the basic version of AddCommandLine fornthe standard formats supported.

Short keys start with a single dash ("-") and are mapped to the main key name (without prefix), and can be used with either equals or space. The single dash mappings are intended to be used for shorter alternative switches.

Note that a single dash switch cannot be accessed directly, but must have a switch mapping defined and accessed using the full key. Passing an undefined single dash argument will cause as FormatException.

There are two formats for short arguments: -k1=value1 -k2 value2.

Alias key definitions start with two dashes ("--") and are mapped to the main key name (without prefix), and can be used in place of the normal key. They also work when a forward slash prefix is used in the command line (but not with the no prefix equals format).

There are only four formats for aliased arguments: --alt3=value3 /alt4=value4 --alt5 value5 /alt6 value6.

A simple console application that has two short and four alias switch mappings defined.

// dart example.dart -k1=value1 -k2 value2 --alt3=value2 /alt4=value3 --alt5 value5 /alt6 value6
void main(List<String> args) {
  final switchMappings = LinkedHashMap<String, String>.from(
    <String, String>{
      '-k1': 'key1',
      '-k2': 'key2',
      '--alt3': 'key3',
      '--alt4': 'key4',
      '--alt5': 'key5',
      '--alt6': 'key6',
    },
  );

  final builder = ConfigurationBuilder()
  ..addCommandLine(args, switchMappings);
  final config = builder.build();

  print('Key1: \'${config["Key1"]}\'');
  print('Key2: \'${config["Key2"]}\'');
  print('Key3: \'${config["Key3"]}\'');
  print('Key4: \'${config["Key4"]}\'');
  print('Key5: \'${config["Key5"]}\'');
  print('Key6: \'${config["Key6"]}\'');
}

Implementation

ConfigurationBuilder addCommandLine(Iterable<String> args,
    [LinkedHashMap<String, String>? switchMappings]) {
  add(
    CommandLineConfigurationSource(
      args: args,
      switchMappings: switchMappings,
    ),
  );
  return this;
}