gistfile1.rb

require 'shellwords'

class Widget
  
  def self.parse_widgets(content)
    regex = /\[widget (.+)\]/
    content =~ regex
    params = Hash[*Shellwords.shellwords($1).map{ |s| s.split('=', 2) }.flatten]
    widget = Kernel.const_get(params.delete("type")).render(params)
    widget ? content.gsub(regex, widget) : content
  end

end

# Example:
#
content = "[widget type=Feed src=http://example.com/rss]"
Widget.parse_widgets(content)
# This will result in a call like this:
Feed.render("src" => "http://example.com/rss")