Ruby Buzz Forum - Watching changes

Articles |
News |
Weblogs |
Books |
Forums

Artima Forums | Articles | Weblogs | Java Answers | News

Sponsored Link •

Ruby Buzz Forum
Watching changes

0 replies on 1 page.

Welcome Guest
Sign In

Back to Topic List

Reply to this Topic

Search Forum

Threaded View


Previous Topic		Next Topic

Flat View: This topic has 0 replies on 1 page

Matt Williams

Posts: 466
Nickname: aetherical
Registered: Feb, 2008

Matt Williams is a jack-of-all trades living in Columbus, OH.

Watching changes

Posted: Apr 18, 2008 9:39 AM

This post originated from an RSS feed registered with Ruby Buzz by Matt Williams.
Original Post: Watching changes Feed Title: Ruby Blender Feed URL: http://feeds2.feedburner.com/RubyBlender Feed Description: This blog contains short-ish ruby tips, hints, and techniques.	Latest Ruby Buzz Posts Latest Ruby Buzz Posts by Matt Williams Latest Posts From Ruby Blender

The ruby2ruby gem allows you to peer into a class's methods and watch changes due to metaprogramming.

ruby2ruby is a gem created by the Seattle Ruby Brigade. You can install it, like any other gem, with gem install ruby2ruby. Once installed, it lets you peer inside a Class' methods.


$ irb
irb(main):001:0> require 'rubygems'
=> true
irb(main):002:0> require 'ruby2ruby'
=> true
irb(main):003:0> class Foo
irb(main):004:1> attr_accessor :fud
irb(main):005:1> def initialize(fud)
irb(main):006:2> @fud = fud
irb(main):007:2> end
irb(main):008:1> end
=> nil
irb(main):009:0> Ruby2Ruby.translate Foo
=> "class Foo < Object\n  attr_reader :fud\n  \n  attr_writer :fud\n  \n  def initialize(fud)\n    @fud = fud\n  end\nend"

Here I've created a simple class. One thing that is interesting, the interpreter expands attr_accessor into both attr_reader and attr_writer for me automatically. One of the requirements of Ruby2Ruby is that it works on Classes, not on instances:


irb(main):010:0> f=Foo.new(5)
=> #<Foo:0x2b82e560d608 @fud=5>
irb(main):011:0> Ruby2Ruby.translate f
NoMethodError: undefined method `instance_methods' for #<Foo:0x2b82e560d608 @fud=5>
        from /usr/lib/ruby/gems/1.8/gems/ParseTree-2.1.1/lib/parse_tree.rb:115:in `parse_tree'
        from /usr/lib/ruby/gems/1.8/gems/ParseTree-2.1.1/lib/parse_tree.rb:99:in `parse_tree'
        from /usr/lib/ruby/gems/1.8/gems/ParseTree-2.1.1/lib/parse_tree.rb:71:in `translate'
        from /usr/lib/ruby/gems/1.8/gems/ruby2ruby-1.1.8/lib/ruby2ruby.rb:31:in `translate'
        from (irb):11
irb(main):012:0> Ruby2Ruby.translate f.class
=> "class Foo < Object\n  attr_reader :fud\n  \n  attr_writer :fud\n  \n  def initialize(fud)\n    @fud = fud\n  end\nend"

We can compare the code as it changes, too:


irb(main):013:0> class Foo
irb(main):014:1> def something(bar)
irb(main):015:2> puts bar
irb(main):016:2> end
irb(main):017:1> end
=> nil
irb(main):018:0> Ruby2Ruby.translate Foo
=> "class Foo < Object\n  attr_reader :fud\n  \n  attr_writer :fud\n  \n  def initialize(fud)\n    @fud = fud\n  end\n  \n  def something(bar)\n    puts(bar)\n  end\nend"

There's a lot more which can be done here, and it will be the subject of a further entry.

Read: Watching changes

Previous Topic

Next Topic


	Web Artima.com