ripl

ruby interactive print loop - A light, modular alternative to irb

cldwalker
389
22
Ruby

== Description

ripl is a light shell that encourages common middleware for shells i.e. rack for
ruby shells. It is also a 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 i.e.
{ripl-play}[https://github.com/cldwalker/ripl-play#readme]. This
customizability makes it easy to build custom shells (i.e. for a gem or
application) and complex shells (i.e. for the
{web}[https://github.com/cldwalker/nirvana#readme]). Works on ruby 1.8.7 and
greater.

== Install

If you have {readline}[http://cnswww.cns.cwru.edu/php/chet/readline/rltop.html],
install ripl with:

gem install ripl

If you don’t have readline, first install ripl with {a pure ruby
readline}[https://github.com/luislavena/rb-readline#readme]:

gem install ripl rb-readline -- --without-readline

Then, add the following to ~/.riplrc:

Ripl.config[:readline] = 'rb-readline'
Ripl.config[:completion] = {:readline => :ruby }

== Setup

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

# Adds multi-line evaluation
gem install ripl-multi_line

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

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

== Usage

$ ripl
>> ...

== Documentation

To view ripl’s man page:

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

To view ripl’s documentation online, read the source
or the html version.

== 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}[https://github.com/cldwalker/ripl-irb#readme]
gem. This ripl plugin fakes irb’s existence and points to ripl equivalents for
your irb configurations. 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, quit or press Ctrl-D to exit
    • 6 common commandline options: -f, -r, -I, -d, -h, -v
    • IRB.conf -> Ripl.config
    • Handles Ctrl-C quietly
  • Enhancements over irb
    • ~290 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
    • Custom commandline options can be added via a plugin
    • ~/.irbrc errors caught
    • Well-integrated internationalization (see {ripl-i18n}[https://github.com/cldwalker/ripl-i18n#readme])
  • Different from irb

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.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 Ripl 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}[https://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 => MyClass.instance_eval{ 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- 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}[https://github.com/cldwalker/ripl-rails#readme].

== Credits

  • janlelis and godfat for bug fix and tweaks
  • JoshCheek for bug fixes
  • postmodern for windows fixes and no history support

== Bugs/Issues

Please report them {on github}[https://github.com/cldwalker/ripl/issues].

== Contributing

{See here}[http://tagaholic.me/contributing.html]

== Ripl Plugins

== Ripl Shells

Shells built on top of ripl:

== More Ripl Links

== Irb Alternatives

Some other irb alternatives to check out: