[Python-ideas] Extend module objects to support properties

Thu Jan 31 05:22:50 CET 2013

On 01/30/2013 05:53 PM, Larry Hastings wrote:
>> On 01/30/2013 04:45 PM, Steven D'Aprano wrote:
>> On 31/01/13 03:42, Larry Hastings wrote:
>>>>> Also, I'm not sure there are any existing globals that we'd want to
>>> convert into properties.
>>>> How about this?
>>>> math.pi = 3
>>>> which really should give an exception.
>>>> (I'm sure there are many others.)
>> Well, hmm. The thing is, properties--at least the existing
> implementation with classes--doesn't mesh well with direct access via
> the dict. So, right now,
>> >>> math.__dict__['pi']
> 3.141592653589793
>> If we change math.pi to be a property it wouldn't be in the dict
> anymore. So that has the possibility of breaking code.

So make the property access the __dict__:
--> class Test(object):
... @property
... def pi(self):
... return self.__dict__['pi']
... @pi.setter
... def pi(self, new_value):
... self.__dict__['pi'] = new_value
...
--> t = Test()
--> t
<__main__.Test object at 0x7f165d689850>
--> t.pi = 3.141596
--> t.pi
3.141596
--> t.__dict__['pi'] = 3
--> t.pi
3
~Ethan~