file.rb

  def files(first_path, glob_path, &block)
    # With this block, there is no problem.
    # block = :to_s.to_proc
    iteration = proc do |num, path|
      tmppath = "#{Dir.tmpdir}/#{path}"
      ::FileUtils.mkdir_p(::File.dirname(tmppath))
      ::File.open(tmppath, 'w+') {|f| f.puts(block.call(num))}
      Battuta::File(tmppath).path = path
    end
    iteration[0, first_path]
    1.upto(self - 1) {|num| iteration[num, glob_path.sub('%N%', num.to_s)]}
    nil
  end
end

me = Battuta::File.new
puts ::ERB.new(me.content).result(binding)

me_content.erb

<% 8.files me.path, me.path.sub('.erb', '.%N%.erb') do |n| %>
<%= n %>
<% end %>

result.txt

first file:

0

second file:

0

1

third file:

0

1

2

fourth file:

0

1

2

3

and so on