152 

   153 

   154 class DynaFieldMetaclass(type):

   155   """The DynaField Meta class, adding support for dynamic properties.

   156 

   157   The new DynaField class that is created by class function is only

   158   modified slightly. The only difference is that if the field class has

   159   a dynaproperties property, it will be used to define additional properties

   160   for the field.

   161 

   162   The 'dynaproperties' property (if present), is expected to be iterable as a

   163   dictionary (with iteritems). The keys are used as the property names,

   164   and the values are used as the property value.

   165   """

   166 

   167   def __new__(cls, name, bases, attrs):

   168     """See djangoforms.ModelFormMetaclass on how the __new__ method

   169     is used, for an explanation on how this class modifies the default

   170     behavior, see the DynaFormMetaclass's docstring.

   171     """

   172 

   173     # Retrieve the Meta class, if present

   174     dynaproperties = attrs.get('dynaproperties', {})

   175 

   176     for key, value in dynaproperties.iteritems():

   177       attrs[key] = value

   178 

   179     # Leave the rest to type

   180     return super(DynaFieldMetaclass, cls).__new__(cls, name, bases, attrs)

   181 

   182 

   183 def newDynaField(field, base, passthrough):

   184   """Creates a new form DynaField class.

   185 

   186   The returned class extends base, but with the following additions:

   187   * It has a dynaproperties attribute as extracted from field.

   188   * It's __metaclass__ is set to DynaFieldMetaclass (which inherits from

   189   the default type class).

   190 

   191   See DynaFieldMetaclass for an explanation on how the dynaproperties

   192   property is used to construct the DynaForm class.

   193   """

   194 

   195   # pass only known accepted arguments to super

   196   init_args = dicts.filter(field, passthrough)

   197 

   198   properties = field.copy()

   199 

   200   # all pass through arguments are handled by super

   201   for key in passthrough:

   202     if key in properties:

   203       del properties[key]

   204 

   205   class DynaField(base):

   206     """The dynamically created Field class.

   207     """

   208 

   209     __metaclass__ = DynaFieldMetaclass

   210     dynaproperties = properties

   211 

   212     def __init__(self):

   213       """Pass through the init args to super.

   214       """

   215 

   216       super(DynaField, self).__init__(**init_args)

   217 

   218   return DynaField