From: Gunther Diemant <g.diemant@...>
Date: 2011-12-08T17:18:31+09:00
Subject: Re: Rake question

Put the transform task definition in front of your each loop.
You only create the task inside this loop.

task :transform do
end

my_files.each do |file|
  file ...
  task :transform => file
end
next_file = 'transformed_files.txt'
file next_file => :transform do
# Do something with all transformed files to produce 1 output file
end