pep 8 constants
Gabriel Genellina
gagsl-py2 at yahoo.com.ar
Tue Feb 24 22:52:45 EST 2009
En Tue, 24 Feb 2009 22:52:20 -0200, Ethan Furman <ethan at stoneleaf.us>
escribió:
> Steve Holden wrote:
>> Brian Allen Vanderburg II wrote:
>>
>>> One idea to make constants possible would be to extend properties to be
>>> able to exist at the module level as well as the class level:
>>>
>>> @property
>>> def pi():
>>> return 3.14159.....
>>>
>>> print(pi) # prints 3.14159....
>>> pi=32 # Raise an error Cannot set attribute ...
>>>
>> I don't understand why this would print 3.14159 ... instead of
>> <function
>> __math__.pi>, or whatever.
>> property would clearly have to do something very different in module
>> scope in order to make this work.
>> regards
>> Steve
>
> --> class tester(object):
> ... @property
> ... def pi(self):
> ... return 3.141596
> ...
> --> testee = tester()
> --> testee.pi
> 3.1415959999999998
>
> Looks like that's how property works, so the same behavior on a module
> level would do as Brian suggests.
Note that:
- you defined the property inside the *class* tester
- then, you created an *instance* of such class
- you retrieve pi from the instance
- if you retrieve pi from the class (tester.pi), you get a property
object, not a float.
- if you directly attach the property to the instance, testee.pi returns
a property object, not a float.
Finally, consider that modules are instances of type `module`; all modules
are instances of the same type.
How do you propose to make properties work at the module level?
--
Gabriel Genellina
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