Jekyll plugin to render LESS (lesscss.org) files during generation.

lessjs.rb

module Jekyll
  
  class LessCssFile < StaticFile
    def write(dest)
      # do nothing
    end
  end
  
  class LessJsGenerator < Generator
    safe true
    priority :low
    
    def generate(site)
      src_root = site.config['source']
      dest_root = site.config['destination']
      less_ext = /\.less$/i
      lessc_bin = site.config['lessc'] || 'lessc'
      
      # static_files have already been filtered against excludes, etc.
      site.static_files.each do |sf|
        next if not sf.path =~ less_ext
        
        site.static_files.delete(sf)
      
        less_path = sf.path
        css_path = less_path.gsub(less_ext, '.css').gsub(src_root, dest_root)
        relative_dir = File.dirname(css_path).gsub(dest_root, '')
        file_name = File.basename(css_path)
        
        FileUtils.mkdir_p(File.dirname(css_path))
        
        begin
          command = [lessc_bin, 
                     less_path, 
                     css_path
                     ].join(' ')
          puts 'Compiling LESS: ' + command
          puts `#{command}`
          raise "LESS compilation error" if $?.to_i != 0
        end
        
        # Add this output file so it won't be "cleaned away"
        site.static_files << LessCssFile.new(site, site.source, relative_dir, file_name)
      end
    end
    
  end
end

Cool! I'm planning to bundle this up with a few other plugins and stick it in a repo. There's an open ticket on the Jekyll project discussing workarounds for the new cleaning -- this is actually one of the cleaner workarounds. See jekyll/jekyll#268 for that.

Hello. I have found a bug in this logic, at least when I am running it locally. By modifying the site.static_files array in the loop there is the potential for processing elements twice or skipping some entirely.

My fix is to use a copy of the array, so:
site.static_files.dup.each do