Drudge

A gem that enables you to write command line automation tools using Ruby 2.0.

Usage

Given a binary file called cli:

#!/usr/bin/env ruby 

require 'drudge'

class Cli < Drudge

  desc "Greets people"
  def greet(from, opening = 'Hi', *messages,  to)
    puts "#{from} says #{opening}, #{messages.join(', ')} to #{to}"
  end
end

Cli.dispatch

Running:

$ ./cli greet Santa 'good day to you' Joe
Santa says Hi, good day to you to Joe

$ ./cli greet Santa Greetings 'how do you do?' Joe
Santa says Greetings, how do you do? to Joe

$ ./cli
error: expected a command:

  cli
      ^

$ ./cli great Santa Joe
error: unknown command 'great':

    cli great Santa Joe
        ~~~~~

$ ./cli greet
error: expected a value for <from>:

    cli greet
              ^

$ ./cli greet Santa
error: expected a value for <to>:

    cli greet Santa
                    ^

Approach

The philosphy of Drudge is to provide a very thin layer over normal Ruby constructs such as classes and methods that exposes them via a command line interface.

This layer interprets the command line instruction and invokes the identifed ruby method using a very simple resolution method. From then on, it's just normal Ruby! No special life-cycles, etc.

Even though this layer is simple, it is built to produce excellent error messages on wrong command line input.

Drudge is built for Ruby 2 with keyword arguments in mind.

Why not Thor?

Drudge was inspired by the great work folks did in Thor.

The problem with Thor is that it tries to be two things at once: a build tool (aimed on replacing rake) and an automation tool.

This introduces a number of unnecessary complexities:

• there are rake-like namespaces but also sub commands for automation. These two concepts have a number of nasty interactions which result in many small but annoying bugs

• it is meant to be used a a stand-alone tool (by invoking thor which will look for a Thorfile) but also as a library for building your own tools. This too produces complexities and unwanted interactions in the Thor codebase

• Thor skews the normal Ruby class/method model towards the command line interface and introduces some 'suprises' for the user (e.g. the Thor-subclass gets instantieated every time a method/command is called, something that is not usually expected)

In contrast, Drudge's aim is simple: a library for building command-line automation tools with the aim of transferring you (conceptionally) from the command line interface into Ruby and then letting you use build your tool in a familiar environement.

License

Released under the MIT License. See the LICENSE file for further details.