Opal: Ruby runtime for javascript

Homepage: http://opalscript.org
Github: http://github.com/adambeynon/opal

Description

Opal is a Ruby runtime and standard library designed to run directly on top of javascript. It can be run within the browser or on the command line through the bundled build tools. Opal includes a parser/compiler that builds ruby ahead of time directly into javascript that runs with the bundled runtime.

Features

• method_missing support when calling undefined methods in debug mode
• Full operator overloading ([], []=, +, -, ==, etc)
• Toll free bridges to javascript objects (String, Number, Array etc)
• Inline javascript within ruby code using backticks
• In browser loading of <script type="text/ruby></script> tags
• Generated code is clean and maintains line numbers to ease debugging
• super(), metaclasses, eigenclasses, blocks, yield, block_given?, ranges, arg count errors, lambda, singletons, etc....

Installation

The best way to get started with opal is to clone this repo and use the opal bin file directly:

$ git clone git://github.com/adambeynon/opal.git

Although opal is distributed as a gem, the latest gem release is mostly incompatible with the loading and runtime system for opal, so until a newer gem is released (0.3.5), it is best to stick with the repo.

Try without installing

Browser can be used inside a repl on the http://opalscript.org homepage which gives an IRB style interface for running ruby code which is compiled and evaluated within the browser (no plugins!).

Alternatively the opal runtime and opal parser can be downloaded directly from the extras directory in this repository.

Usage

Opal can be used within in the browser, or on the command line using the build tools. A Nodejs environment is also partially implemented.

Browser

To run within the browser, you can either use the latest build version on the opal website, or clone the build tools as above, and then run the following task in this directory:

$ rake opal

This will place a non minified version ready to run within the browser into extras/opal.js

Compiling ruby sources

To run ruby code in the browser, ruby must either be precompiled to javascript using these build tools, or the opal_dev.js file can parse and compile ruby code referenced in html script tags that use the text/ruby type.

Command line

Opal is bundled with a set of build tools available in the opalite/ directory. These are available when running opal from the command line or including it from ruby sources.

Ruby repl

To run the repl, clone this repo as directed above and run:

$ bin/opal irb

This will act like any other repl to try out commands. The repl relies on therubyracer as its javascript engine.

Running tests

Opal uses a subset of the rubyspec specs for ruby until it reaches a mature enough state to just use rubyspec directly. These tests are found in the spec/ folder. They can be run either through the command line, or built ready to open in the browser.

Running in the browser

To run in the browser, first build the specs (compile into js ready):

$ rake opal_spec

This will build the specs into extras/ so open extras/opal.spec.html in any browser to see how the specs run.

Running on command line

The opal binary has a spec flag which can be passed one or any number of specs. For example, to run the and and && specs from this repo, run:

$ bin/opal spec spec/language/and_spec.rb

Between gem releases every spec will pass. The master branch in this repo may contain broken specs, but these will be fixed before the next gem release and version bump.

Examples

Examples can be found in the examples/ directory in this repo, and rely on extras/opal.js being created using the above commands.