dynobject.py

   1 ## dynobject.py
   2 ## a dynamic object for Python
   3 ## by Sam Fredrickson <kinghajj@gmail.com>, 2007-02-22
   4 ##
   5 ## inspired by Javascript. in JS, you can make objects like this:
   6 ## o = {a: 2, b: 3}
   7 ## o.c = 4
   8 ## o.d = 5
   9 ## ...
  10 ##
  11 ## with dynobject, you can do similar in python:
  12 ## o = dynobject(a=2, b=3)
  13 ## o.c = 4
  14 ## o.d = 5
  15
  16 # ah, metaclasses. here's a use for them. without this metaclass, I couldn't
  17 # use setattr() to define new properties on-the-fly
  18 class __dynobject_meta__(type):
  19         # when you are creating a dynobject, you can pass it keywords
  20         def __call__(self, **kwargs):
  21                 obj = type.__call__(self)
  22                 for key in kwargs:
  23                         setattr(obj, key, kwargs[key])
  24                 return obj
  25
  26 class dynobject(object):
  27         __metaclass__ = __dynobject_meta__
  28
  29         # when you iterate, you get pairs of attribute names and values
  30         def __iter__(self):
  31                 attrs = dir(self)
  32                 for attr in attrs:
  33                         if attr[0:2] != "__" and attr[-3:-1] != "__":
  34                                 yield (attr, getattr(self, attr))
  35
  36         # if you request a nonexistant attribute, you get None rather than an
  37         # error
  38         def __getattribute__(self, attr):
  39                 try:
  40                         return object.__getattribute__(self, attr)
  41                 except:
  42                         return None
  43