Printing the source code of a Ruby block

In Ruby 1.9+ (tested with 2.1.2), you can use https://github.com/banister/method_source

Print out the source via block#source:

#! /usr/bin/ruby
require 'rubygems'
require 'method_source'

def wait &block
  puts "Running the following code: #{block.source}"
  puts "Result: #{yield}"
  puts "Done"
end

def run!
  x = 6
  wait { x == 5 }
  wait { x == 6 }
end

run!

Note that in order for the source to be read you need to use a file and execute the file (testing it out from irb will result in the following error: MethodSource::SourceNotFoundError: Could not load source for : No such file or directory @ rb_sysopen - (irb)

You can do this with Ruby2Ruby which implements a to_ruby method.

require 'rubygems'
require 'parse_tree'
require 'parse_tree_extensions'
require 'ruby2ruby'

def meth &block
  puts block.to_ruby
end

meth { some code }

will output:

"proc { some(code) }"

I would also check out this awesome talk by Chris Wanstrath of Github http://goruco2008.confreaks.com/03_wanstrath.html He shows some interesting ruby2ruby and parsetree usage examples.