System. Commandline option

I read the previous article briefly CommandLine Use of commands , In fact, in a command-line tool , There is another important point , That's the option ——Option, Option is to provide parameters for the command , It's like C# Medium method ,Command It's like the method ,Option Like the parameters of a method , When it comes to parameters, there are parameter types , Shape parameter （ Formal parameter name ）, Empathy ,CommandLine Also have , Look at a tape Option Example ：

// Create root command 
var rootCommand = new RootCommand(" This is a command line tool ： Dan cat ");
rootCommand.SetHandler(() =>
{
    Console.WriteLine(" Welcome to use 《 Dan cat 》");
});
// Create subcommands  show
var showCommand = new Command("show", " Show me some information ");
// Create subcommand options  times  Alias  t
var timesOption = new Option<int>(name: "--times", description: " Number of times displayed ", getDefaultValue: () => 1)
{
    IsHidden = true,
};
timesOption.AddAlias("-t");
// Add options to show In command 
showCommand.AddOption(timesOption);
// Set command show The action performed , This is to take times Parameters , Type is integer 
showCommand.SetHandler((int times) =>
{
    for (var i = 0; i < times; i++)
    {
        Console.WriteLine($" This is a 《 Dan cat 》 Of show command , Display times ={i}");
    }
}, timesOption);
// Add command show To   In the root command 
rootCommand.Add(showCommand);
await rootCommand.InvokeAsync(args);

Options can be added , Add description , Set the default value , Also set whether you can hide , Or it is required , Options are displayed in the command execution method SetHandler receive .

Running results ,-t 5, loop 5 Time ; If the type of the option parameter is incorrect , There will be hints. ; Do not enter option parameters , Default straight 1, Here is a friendly offer Func<int>, Instead of a value , Because the default value may depend on other resource information , Not a constant .