Ruby block to string instead of executing [duplicate]

Question

Take this example:

write_as_string { puts 'x' }

I then want to be able to do

def write_as_string(&block)
  puts block.to_s
end

When I execute this, I want the output to be:

"puts 'x'"

I want to be able to receive the block and get the actual code for the block instead of executing it.

Motivation: Creating a DSL, I want to the mock to be converted into a number of other method calls, hidden from the calling code - using existing objects and methods without monkey patching them.

Any ideas on this would be great!

Thanks

Ben

Answer 1

If you're on Ruby 1.9, you can use the sourcify gem. It provides Proc#to_source, which is like ParseTree's Proc#to_ruby.

When using sourcify, if you have nested procs in your source code, you might have to help it along with the :attached_to option:

## (Works in Ruby 1.8) Using ParseTree (with parse_tree_extensions)
block.to_ruby
## (Works in Ruby 1.9) Using sourcify
block.to_source
## Try this if you get Sourcify::NoMatchingProcError or Sourcify::MultipleMatchingProcsPerLineError
block.to_source :attached_to => :name_of_block_in_source_code

I posted about ParseTree and Ruby 1.9 in my company's blog.

Answer 2

Duplicate: Printing the source code of a Ruby block

sudo gem install ParseTree
sudo gem install ruby2ruby

then

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

def block_as_string &block
    block.to_ruby
end

results in

irb(main):008:0> block_as_string {puts 'x'}
=> "proc { puts(\"x\") }"