therubyracer/README.md

therubyracer

• http://github.com/cowboyd/therubyracer
• http://groups.google.com/group/therubyracer
• irc://irc.freenode.net/therubyracer

DESCRIPTION:

Embed the V8 Javascript interpreter into Ruby.

FEATURES/PROBLEMS:

• Evaluate Javascript from with in Ruby
• Embed your Ruby objects into the Javascript world
• Manipulate JavaScript objects and call JavaScript functions from Ruby
• API compatible with the The Ruby Rhino (for JRuby: http://github.com/cowboyd/therubyrhino)

SYNOPSIS:

gem install therubyracer (stable)
gem install therubyracer --pre (bleeding edge)

then in your ruby code

require 'v8'

evaluate some simple javascript

cxt = V8::Context.new
cxt.eval('7 * 6') #=> 42

embed values into the scope of your context

cxt['foo'] = "bar"
cxt.eval('foo') # => "bar"

embed ruby code into your scope and call it from javascript

cxt["say"] = lambda {|word, times| word * times}
cxt.eval("say('Hello', 3)") #=> HelloHelloHello

embed a ruby object into your scope and access its properties/methods from javascript

class MyMath
  def plus(lhs, rhs)
    lhs + rhs
  end
end

cxt['math'] = MyMath.new
cxt.eval("math.plus(20,22)") #=> 42

make a ruby object be your global javascript scope.

math = MyMath.new
V8::Context.new(:with => math) do |cxt|
  cxt.eval("plus(20,22)") #=> 42
end

you can do the same thing with Object#eval_js

math.eval_js("plus(20,22)")

Different ways of loading javascript source

In addition to just evaluating strings, you can also use streams such as files.

evaluate bytes read from any File/IO object:

File.open("mysource.js") do |file|
  cxt.eval(file, "mysource.js")
end

or load it by filename

cxt.load("mysource.js")

Safe by default

The Ruby Racer is designed to let you evaluate javascript as safely as possible unless you tell it to do something more dangerous. The default context is a hermetically sealed javascript environment with only the standard javascript objects and functions. Nothing from the ruby world is accessible at all.

For ruby objects that you explicitly embed into javascript, by default only the public methods below Object are exposed by default. E.g.

class A
  def a
    "a"
  end

  def to_s
    super
  end
end

class B < A
  def b
    "b"
  end
end


V8::Context.new do |cxt|
  cxt['a'] = A.new
  cxt['b'] = B.new
  cxt.eval("a.a") # => 'a'
  cxt.eval("b.b") # => 'b'
  cxt.eval("b.a") # => 'a'
  cxt.eval("b.to_s") # => #<B:0x101776be8> (because A explicitly defined it)
  cxt.eval("b.object_id") #=> undefined, object_id is on Object
end

Dangerous by Demand

All aspects of ruby embedding are pluggable on a per context basis, including the visibility of ruby libraries and classes. If needed, you can expose more aspects of the It is possible to override this safe behavior.

REQUIREMENTS:

• python >= 2.5 (required to compile v8)
• C++ compiler

DEVELOP

• git clone git://github.com/cowboyd/therubyracer.git
• cd therubyracer
• rake compile

LICENSE:

(The MIT License)

Copyright (c) 2009,2010,2011 Charles Lowell

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.