[Python-ideas] Properties for classes possible?

[Sven R. Kunze]

Sounds more like Thomas is looking for an Pythonic solution without 
messing around with sys.modules or metaclasses.

I personally like the proposals on StackOverflow and don't see why it 
couldn't be made to work out of the box:


class MyClass:
     @classproperty
     def prop(cls):
         return '42'

# module property
@property
def prop(mod):
     return '42'



On 20.08.2015 09:47, Nathaniel Smith wrote:
> On Thu, Aug 20, 2015 at 12:20 AM, Andrew Barnert via Python-ideas
> <python-ideas at python.org> wrote:
>> Modules are a more serious problem, because there's no immediate way to specify the type for a module object. You can work around it by, e.g., declaring a module subclass, copying the module's dict to an instance of that subclass, then replacing the entry in sys.modules, but this is more than a little ugly.
>>
>> There have been proposals to allow modules to specify a type (e.g., something similar to the way __metaclass__ worked in 2.x), and to make it easier to hook the import machinery to create modules of a custom type, and probably other variations on this. You might want to search this list and -dev for previous ideas, to find one you think should be reconsidered.
> This is already done :-). Python 3.5 allows a module to contain code like:
>
> class MetaModule(types.ModuleType):
>      @property
>      def some_attribute(self):
>          print("Accessing module.some_attribute")
>          return 1
>
> sys.modules[__name__].__class__ = MetaModule
>
> See also
>
>      https://pypi.python.org/pypi/metamodule
>
> for utility code and a polyfill back to ancient Pythons.
>
> -n
>