Unnamed

#!/usr/bin/env python# encoding: utf-8def save_desc(self, desc, *args, **kwargs):   self.desc = desc   self.__init_orig__(*args, **kwargs)class DescMetaclass(type):                                                                def __new__(cls, name, bases, attrs):      if not name == 'Field':         attrs['__init_orig__'] = attrs['__init__']         attrs['__init__'] = save_desc      return type.__new__(cls, name, bases, attrs)   class Field(object):      __metaclass__ = DescMetaclass   def __init__(self, widget=None, required=True):      self.d={}      self.d['widget'] = widget      self.d['required'] = required         def render(self):      print self.desc      print self.dclass RegExpField(Field):      def __init__(self, widget=None, required=True, regexp=None, caseSensivity=False):      Field.__init__(self, widget=widget, required=required)      self.d['regexp'] = regexp      self.d['caseSensivity'] = caseSensivity   def main():        t=RegExpField('aaaa', regexp='.+', widget=123)    t.render()if __name__ == '__main__':    main()