accessing value of a python @property -

i'm trying rework oauthlib implementation pyramid app , ran issue default values on @property decorated class defs.

i somehow exposing property objects, , not calling/executing them.

can suggest way 'execute' these properties? seems calling fget object/none works:

self.propertyname.fget(self) 

this seems awkward though -- entire issue. seem implementing wrong way.

the context of problem, trying load values configuration dict , falling onto property of base class. basic form below, , advice on better implementation gladly accepted.

class parent(object):     @property     def fieldname(self):         """returns tuple"""         return (1, 10)  class child(parent):     @property     def fieldname(self):         """returns tuple"""         return self._config.get('fieldname',                                  parent.fieldname                                 ) 

property objects descriptors, means automatically bound instance when accessed attribute (this how methods created).

if wanted access parent property object, bind manually calling descriptor.__get__() method , passing in self:

parent.fieldname.__get__(self)) 

the property.fget() method original, un-decorated function object. you'd call unbound method, you'd pass in self manually again:

parent.fieldname.fget(self) 

or bind method, call:

parent.fieldname.fget.__get__(self)() 

last, not least, use super() object take care of binding you:

super(child, self).fieldname 

which finds next object in mro (method resolution order) of class hierarchy has fieldname attribute , binds explicit example above.

personally, prefer super() option; best documents want access original, overridden property.

demo:

>>> class parent(object): ...     @property ...     def fieldname(self): ...         """returns tuple""" ...         return (1, 10) ...  >>> class child(parent): ...     @property ...     def fieldname(self): ...         """returns tuple""" ...         return self._config.get( ...             'fieldname',  ...             super(child, self).fieldname) ...  >>> child = child() >>> child._config = {} >>> child.fieldname (1, 10) >>> child._config['fieldname'] = ('foo', 'bar') >>> child.fieldname ('foo', 'bar')