Mapping Properties To Options

IMPORTANT NOTE: This wiki refers to latest stables, if a beta version is available in github master branch please refer to Latest Version.

Mapping Properties to Options

You can map almost any data type to command line option.

Scalars

Scalar values are mapped using OptionAttribute type. Let's define a string option.

class Options
{
  [Option('p', "person-to-greet", DefaultValue = "World")]
  public string PersonToGreet { get; set; }

  // Version 1.9.4.91+, use char for shortname
  [Option('f', "friend-to-greet", DefaultValue = "Someone")]
  public string FriendToGreet { get; set; }
}

Everything passed to the -p or --person-to-greet option will be loaded into the Options::PersonToGreet instance property. This option is not required (default Required = false), so if not specified the property will contain the string "World".

Both app -p Jhonny and app --person-to-greet Jhonny will be accepted.

You can map without problems also enum (System.Enum) and nullable (Nullable<T>) values:

enum GreetType
{
  Hello,
  Bye,
  Regards
}

class Options
{
  [Option('g', "greet-type")]
  public GreetType SpecifiedGreetType { get; set; }

  [Option('t', "times-to-greet")]
  public int? TimesToGreet { get; set; }
}

When specifying enum values, you don't need to respect case. Both app -g bye and app --greet-type REGARDS are allowed.

Arrays

To map an array you need to use the OptionArrayAttribute type as in following sample:

class Options
{
  [OptionArray('v', "values", DefaultValue = new double[] {.1, .2, .3})]
  public double[] Temperatures { get; set; }
}

You can even specify a default when working with an array. All values specified after an OptionArray will be loaded into the array.

$ app -v 1.9 2.3 5.3 12.4 9.1334
$ app --values 192.9 .3 1.23 .324 3.3323

The parser is culture-sensitive. If you would like to subordinate the parsing process to a particular culture, just change the current thread culture:

Thread.CurrentThread.CurrentCulture = new CultureInfo("en-US");

Lists

The OptionListAttribute allows you to explicitly manage a list of strings from command line. The following target class:

class Options
{
  [OptionList('t', "tags")]
  public IList<string> Tags { get; set; }
}

will let accept a command line like these ones:

$ app -t csharp:vbnet:cpp
$ app -tpython:ruby
$ app --tags nodejs:sinatra:nancyfx:fubumvc

Lists are also used to capture all values not parsed as options. This job is done by ValueListAttribute.

class Options
{
  [Option('p', "person-to-greet", DefaultValue = "World")]
  public string PersonToGreet { get; set; }

  [ValueList(typeof(List<string>), MaximumElements = 2)]
  public IList<string> OtherStuff { get; set; }
}

Typing the following at command line:

$ app -p Someone Chair Table Pen

the parser will collect the string "Someone" in Options::PersonToGreet and other values ("Chair", "Table" and "Pen") in Options::OtherStuff.

Implicit Name

Now if you use the Option parameterless constructor, the library infers it from the property name (and acquires in lower case).

class Options
{
  [Option]
  public bool Verbose { get; set; } // --verbose

  [Option('q')]
  public bool Quiet { get; set; }   // -q
}