== Description

ripl is a light, modular alternative to irb. Like irb, it loads ~/.irbrc, has autocompletion and
keeps history in ~/.irb_history.  Unlike irb, it is highly customizable via plugins and supports
commands.  This customizability makes it easy to build custom shells (i.e. for a gem or application)
and complex shells (i.e. for the {web}[http://github.com/cldwalker/nirvana]).

== Install

Install the gem with:

    sudo gem install ripl

To make your first ripl experience smoother, also install these plugins:

    # Adds multi-line evaluation
    sudo gem install ripl-multi_line

    # Ignore errors caused by irb-specific configuration in ~/.irbrc
    sudo gem install ripl-irb

    # Add to ~/.riplrc
    require 'ripl/multi_line'
    require 'ripl/irb'

== Usage

    $ ripl
    >> ...

To view ripl's man page:

    # If installed with rubygems
    $ gem install gem-man
    $ gem man ripl

    # If installed with rip, man page is automatically installed
    $ man ripl

== Coming from irb

When first trying ripl, you may experience errors in your ~/.irbrc due to an irb-specific
configuration. In order to have ripl and irb coexist peacefully, you should silence these errors.
To silence them without touching your ~/.irbrc, install the ripl-irb gem. This ripl plugin fakes
irb's existence, effectively ignoring irb-specific configuration. Otherwise, if you don't mind
modifying ~/.irbrc, wrap your irb-specific configuration in a block as follow:

    if defined? IRB
      IRB.conf[:BLAH] = 'blah'
      # ...
    end

== Comparison to Irb

* Similar to irb
  * Reads ~/.irbrc on startup
  * Appends to ~/.irb_history on exit
  * Autocompletion (from bond)
  * _ for last result
  * Type 'exit' or Ctrl-D to exit
  * 6 common commandline options: -f, -r, -I, -d, -h, -v
  * IRB.conf -> Ripl.config
* Enhancements over irb
  * ~250 lines (doc included) vs irb's 5000+ lines
  * Easily extendable with plugins
  * Tests and documentation!
  * Customizable completion and completion of method arguments (from bond)
  * Easy to create custom shells for gems and apps i.e. Ripl.start
  * Easy to create and invoke ripl commands
  * Create console commands in a simple, modular way
  * ~/.irbrc errors caught
* Different from irb
  * No multi-line evaluation by default (there is a plugin. See Available Plugins below).
  * No irb subsessions or workspaces
  * No IRB.conf features i.e. preconfigured prompts and auto indent

Note: Irb features not in ripl can be implemented as plugins.

== Plugins

A ripl plugin is a module that is included into Ripl::Shell or extended into Ripl::Runner. Being simply modules,
they can be packaged as gems and reused across shells as needed.  ripl highly encourages plugins by
loading them as early as possible and allowing them to extend most of ripl's functionality.

As an example plugin, let's color error messages red:

    require 'ripl'

    # To try place in ~/.riplrc
    module Ripl
      module RedError
        def format_error(error)
          "\e[31m#{super}\e[m"
        end
      end
    end
    Ripl::Shell.send :include, Ripl::RedError

Note this plugin extends format_error() by invoking the original format_error() with super. This is
possible for any method that is available for extension by plugins. To see what methods are available for
extension, see Ripl::Shell::API and Ripl::Runner::API.

If we want to add a config for this plugin, we can simply add a key to Ripl.config that matches the
underscored version of the plugin name i.e. Ripl.config[:red_error].

For available plugins, see Available Plugins below.

== Configuration

Since ripl is highly customizable, it loads ~/.riplrc before it does anything. This ruby file should
require and/or define plugins. Any ripl configurations via Ripl.config should also be done here.
For an example riplrc, see {mine}[http://github.com/cldwalker/dotfiles/tree/master/.riplrc].

== Create Custom Shells

Creating and starting a custom shell is as simple as:

    require 'ripl'
    # Define plugins, load files, etc...
    Ripl.start

Ripl.start takes options to customize your shell. For example if you wanted to
start on a specific binding:

    Ripl.start :binding => my_desired_binding

== Create Commands

If you want to invoke your custom shell with ripl, make it a ripl command.
To create one, create an executable in the format ripl-<command> and make sure it's in your shell's
$PATH. For example, the file 'ripl-my_gem' would be invoked with `ripl my_gem`. Note that with your
command you can take arguments and parse your options as you please. For an example command,
see {ripl-rails}[http://github.com/cldwalker/ripl-rails].

== Available Plugins

* {ripl-rails}[http://github.com/cldwalker/ripl-rails] : script/console for ripl
* {ripl-color_error}[http://github.com/cldwalker/ripl-color_error] : colorize errors
* {ripl-multi_line}[http://github.com/janlelis/ripl-multi_line] : evaluate multiple lines
* {ripl-after_rc}[http://github.com/cldwalker/ripl-after_rc] : provide blocks to run after ~/.irbrc is loaded
* {ripl-irb}[http://github.com/cldwalker/ripl-irb] : smooths transition from irb
* {ripl-commands}[http://github.com/cldwalker/ripl-commands] : adds ripl commands similar to irb's commands
* {ripl-color_streams}[http://github.com/janlelis/ripl-color_streams] : colorizes stderr + stdout
* {ripl-color_result}[http://github.com/janlelis/ripl-color_result] : colorizes results
* {nirvana}[http://github.com/cldwalker/nirvana]: Not a plugin but rather a web shell built on top of ripl

== Credits
* janlelis for bug fix and tweaks

== irb alternatives
Some other irb alternatives to check out:

* {ir}[http://github.com/raggi/ir]: nice and light
* {irb2}[http://github.com/wycats/irb2]: yehuda katz's partial attempt at rewriting irb
* {dietrb}[http://github.com/alloy/dietrb]: mac and ruby 1.9 specific