Built-in help

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• Built-in help
  • Using an auto-generated help
  • Programmatic usage access
  • Disabling built-in help
  • Customizing help output

ITGlobal.CLI command line parser contains a built-in support for auto-generated help.

Using an auto-generated help

Parser supports two ways to display auto-generated help:

• Using a -h or --help switch

  Append a -h or a --help to a command line to display help an exit. If a command is specified - a help on this command will be printed. Otherwise a generic help will be displayed.

  So, you should type my-app --help to get help on root command and global options.

  

  Typing my-app my command name --help will give you a help on specific command.

  

• Using an implicit help

  If you’re using a CliParser.NewTreeParser() and you run your application without any command line arguments, an implicit help on root commands will be displayed

  

Programmatic usage access

Parser provides a programmatic access to auto-generated help:

var parser = CliParser.NewTreeParser();

// TODO Configure commands and options...
var command = parser.Command("command");

// Get a root usage from parser
var rootUsage = parser.GetUsage();

// Get a command-specific usage from a command
var commandUsage = command.GetUsage();

You may use this data for various purposes, e.g. auto generating MAN pages or text manuals.

Disabling built-in help

In some cases you might need to opt-out built-in help feature.

• To disable -h and --help switches:

  Set CliParser.NewTreeParser()/CliParser.NewSimpleParser()’s disableHelpSwitch method parameter to true:

  var parser = CliParser.NewTreeParser(disableHelpSwitch: true);
  // or
  var parser = CliParser.NewSimpleParser(disableHelpSwitch: true);
  

  This will prevent parser from adding -h/--help switches and their hooks.

• To disable implicit help:

  Set CliParser.NewTreeParser()’s disableImplicitHelp method parameter to true:

  var parser = CliParser.NewTreeParser(disableImplicitHelp: true);
  

  This will prevent parser from adding default OnExecute callback, allowing you to set your own one.

  Note that implicit help is avaiable for CliParser.NewTreeParser() only.

• To disable help command:

  Set CliParser.NewTreeParser()’s disableHelpCommand method parameter to true:

  var parser = CliParser.NewTreeParser(disableHelpCommand: true);
  

  This will prevent parser from adding help command.

  Note that help command is avaiable for CliParser.NewTreeParser() only.

Customizing help output

You may override the way help output is rendered to console. For example, you might need to localize it or to change its visual style.

In order to archieve that, you will need to:

1. Implement a IHelpPrinter interface in a custom class (try using HelpPrinterBase to simplify your code):

   public class MyHelpPrinter : HelpPrinterBase
   {
       // TODO implement required methods
   }
   

2. Pass an instance of IHelpPrinter to ICliParser.UseHelpPrinter() method:

   var parser = CliParser.NewTreeParser();
   parser.UseHelpPrinter(new MyHelpPrinter());