class F(object):
_b = ['d','a','b','c']
def __init__(self, **kwargs):
for i in kwargs.iteritems():
if i[0] in self._b:
self.__dict__[i[0]] = i[1]
else:
raise AttributeError("error")
f = F(c=33, a=1,b=2, d=445)
print f.a
print f.b
print f.d
print f.c
print dir(f)