Generate URL helper methods for Backbone router

generate_urls.coffee

# generates URL functions for each of the routes
#
# #### Example:
#
# Given the following routes
#
#   routes:
#     '/posts/:id'          : 'showPost'
#     '/posts/:id/comments' : 'comments'
#
# this function will generate the functions `showPostUrl` and `commentsUrl`:
#
#   showPostUrl(1)
#   # => /posts/1
#
#   commentsUrl(1)
#   # => /posts/1/comments
#
_generateUrls: () ->

  # for each route
  for route, name of @routes

    # generate the corresponding URL function
    @["#{name}Url"] = ((route) ->
      return ->
        args  = arguments   # arguments passed to the Url function
        index = 0           # argument index
        param = /[:\*]\w+/g # regexp for route fragment parameters

        # replaces each of the parameters in the route fragment
        route.replace param, -> args[index++]
    )(route)