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Create a class-based command

To create a class-based command, you have to create two classes:

  1. one that defines the data associated with the command,
  2. one that implements the logic of the command.

Depending on what basic features you need for your command, you can choose to implement the logic of the command by inheriting from the abstract class CommandBase<THelpedCommandData> or by implementing the interface ICommandHandler<TCommandData>.

Inherit from CommandBase<THelpedCommandData>

The abstract class CommandBase<THelpedCommandData> provides implementation for :

  • an --help option,
  • access to the current IServiceProvider via the property ServiceProvider,
  • access to the current IConsole via the property Console.

When deriving from this class, you have to implement the ExecuteCommandAsync that is called when the value of the --help option is false.

You also have to make your command data class inherit from MGR.CommandLineParser.Command.HelpedCommandData to have the help option implemented. It will also give you access to the ICommandType which describes the current command.

Implement ICommandHandler and CommandData

If you don't need these features, you can implement the interface ICommandHandler<TCommandData>.

The interface defines a method ExecuteAsync to implement which is called to execute the command. It takes two parameters:

  1. The data of the command, of type of the generic type argument TCommandData,
  2. A CancellationToken used to stop the execution of the command.

The method returns a Task<int> that represent the status code of the execution of the command (usually the exit code of the program).

The "data" class must inherit CommandData, that provides a property Arguments (of type IList<string>) that will receive all arguments not mapped to an option. To define your own opptions, you have to add properties to this class.

Customize your command

Learn how to customize your command.

Add options to you command

You can add options to your command by simply adding properties to your "command data" class. The properties can have any type, you just have to be sure there is a converter for this type (see the list of built-in converters).

You can customize the behavior of the options with some annotations (the parser supports the annotations from System.ComponentModel.DataAnnotations):

  • Use System.ComponentModel.DataAnnotations.DisplayAttribute and some of its properties:
    • Name and ShortName to respectively change the long and short form of the option
    • Description to define a description in the auto-generated help for the option,
  • Use any of the System.ComponentModel.DataAnnotations.ValidationAttribute derived class to validate the value provided for the option.

See all details about customizing your options.