gistfile1.rb

require 'sinatra'

# /a/b/:/d matches
# /a%2fb/:/d matches
# /a/b/%3a/d doesn't match
get '/a/b/:/d' do
  'yay 1'
end

# /e/f/:/h matches
# /e%2ff/:/h matches
# /e/f/%3a/h doesn't match
get %r{/e/f/:/h} do
  'yay 2'
end

run Sinatra::Application