Abstract out the binder lookup code from the Binding constructor.

@@ -9,13 +9,7 @@ Rivets = {}
 # Polyfill For String::trim.
 unless String::trim then String::trim = -> @replace /^\s+|\s+$/g, ''
 
-# A single binding between a model attribute and a DOM element.
-class Rivets.Binding
-  # All information about the binding is passed into the constructor; the DOM
-  # element, the type of binding, the model object and the keypath at which
-  # to listen for changes.
-  constructor: (@el, @type, @model, @keypath, options) ->
-    @options = (options ||= {})
+findBinder = (type) ->
   unless binder = Rivets.binders[type]
     binder = Rivets.binders['*']
     for identifier, value of Rivets.binders
@@ -25,12 +19,21 @@ class Rivets.Binding
           binder = value
           args = regexp.exec type
           args.shift()
-            @args = args
 
   if binder instanceof Function
     binder = {routine: binder}
 
-    @binder = binder
+  [binder, args]
+
+# A single binding between a model attribute and a DOM element.
+class Rivets.Binding
+  # All information about the binding is passed into the constructor; the DOM
+  # element, the type of binding, the model object and the keypath at which
+  # to listen for changes.
+  constructor: (@el, @type, @model, @keypath, options) ->
+    @options = (options ||= {})
+
+    [@binder, @args] = findBinder(type)
     @formatters = options.formatters || []
 
   # Applies all the current formatters to the supplied value and returns the