ConsoleApp.CommandLine 1.2.6

Introduction

Tools for building console application.

Installation

Install-Package ConsoleApp.CommandLine

Quick Start

Basics

To start, you need to configure the entry point to the application. Where "ConsoleApp" will be your class with a command handler.

using System

class Program
{
	public static int Main()
	{
		return CommandLine.Run<Program>(CommandLine.Arguments, defaultCommandName: "SayHello")
	}	
	public static int SayHello()
	{
		Console.WriteLine("Hello!");
		return 0;
	}
}

CommandLine.Run relies on reflection to find methods. So they should be static and return int which is Exit Code

Now you can test your application:

myapp.exe SayHello 
#>Hello!
myapp.exe SAYHELLO
#>Hello! -- command name is case-insensitive (parameters are not!)
myapp.exe 
#>Hello! - Too because 'defaultCommandName' is set to 'SayHello'

Parameter bindings

Positional and named parameters

You can add parameters to your command which is automatically binds by name or position

public static int SayHello(string name)
{
	Console.WriteLine("Hello " + name + "!");
	return 0;
}

Testing:

myapp.exe SayHello Mike 
#>Hello Mike!
myapp.exe SayHello --name Jake
#>Hello Jake!

List parameters

You can add array parameter to collect multiple values as shown below:

public static int SayHello(string[] names)
{
	Console.WriteLine("Hello " + string.Join(", ", names) + "!");
	return 0;
}

Testing:

myapp.exe SayHello --names Mike Jake
#>Hello Mike, Jake!

Parameter accepting multiple values can be only named.

Optional parameters

You can make any parameter optional by specifying default value.

public static int ShowOptionalParameter(int myOptionalParam = 100)
{
	Console.WriteLine("My optional parameter is " + myOptionalParam);
	return 0;
}

Testing:

myapp.exe ShowOptionalParameter --myOptionalParam 200
#>My optional parameter is 200
myapp.exe ShowOptionalParameter 300
#>My optional parameter is 300
myapp.exe ShowOptionalParameter
#>My optional parameter is 100

Flag parameters

You can have a flag(true/false) parameter. It's presence is considered to be "True" and absence is "False".

public static int ShowFlag(bool myFlag)
{
	Console.WriteLine(myFlag ? "Flag is set" : "Flag is not set");
	return 0;
}

Testing:

myapp.exe ShowFlag --myFlag
#>Flag is set
myapp.exe ShowFlag
#>Flag is not set

Parameters values starting with hyphen(-) symbol

Negative numbers (such as -1000) are interpreted as values by default. But strings like "-a", "-hello" are interpreted as named parameters. To stop this interpretation you could place bare hyphen:

myapp.exe - --message -hello --class -a

Enforcing positional parameters

You could pass bare double hyphen(--) and anything after it will be threated as positional parameters.

myapp.exe --type message -- value1 value2 value3

No special symbols are interpeted after double hyphen(--) even another double hypthen:

myapp.exe --type message -- -value1 --value2 --value3-- --

Supported Parameter Types

• Primitive types (int, byte, char ...)
• BCL types (String, DateTime, Decimal)
• Nullable types
• Enum types
• Types with TypeConverterAttribute (Point, Guid, Version, TimeSpan ...)
• Types with Parse(string value) method (IpAddress, Guid ...)
• Types with explicit/implicit conversion from string

Сommands Hierarchy

Suppose you want to build a complex API where commands are grouped by purpose.

Example:

myfinance.exe Account Show --id 0a0e0000000

Each group must be defined as method(command) with one CommandLineArguments argument.

public static int Account(CommandLineArguments arguments)
{
	return CommandLine.Run<AccountCommands>(arguments);
}

class AccountCommands
{
	public static int Show()
	{
		// ...
	}
}

where AccountCommands is class with list of commands as described in "Basics".

Commands Description

Your command line application can generate help for the user. This requires to define Help method with following code inside

public static int Help()
{
	return CommandLine.Describe<ConsoleApp>();
}

Testing:

myapp.exe Help
>	HELP

Not too much information 😃

You can decorate the method with DescriptionAttribute attributes to expand 'Help' information.

using System.ComponentModel;

[Description("Display this help.")]
public static int Help()
{
	return CommandLine.Describe<ConsoleApp>();
}

Testing:

myapp.exe Help
>	HELP - Display this help.

You can add these attributes to the methods, parameters and classes. All of them are involved in the generation of reference.

Handling Errors

To catch and handle binding or execution errors you could subscribe on CommandLine.UnhandledException method.

CommandLine.UnhandledException += (sender, args) => Console.WriteLine(args.Exception.ToString());