king kikapu wrote:
> Your example Dennis, work as expected. I understand the mistake i have
> made. But when i try to fix the original code usihn @property now, it
> gives me the same error.
> So, here it is:
>
> class Person(object):
> _age = 0
>
> @property
> def age():
> def fget(self):
> return self._age
> def fset(self, value):
> self._age = value
>
> me = Person()
> me.age = 34
> print me.age
>
>
> I am sure it is something very obvious but my skills does not (yet)
> enable me to figure this out,,,
@decorator
def f():
# ...
is the same as
def f():
# ...
f = decorator(f())
What happens when your age() function is invoked? There is no explicit
return statement, so None is implicitly returned, and
age = property(age())
is the same as age = property(None)
i. e. you get a property with None as the getter. What you want is
>>> def star_property(f):
... return property(**f())
...
>>> class Person(object):
... _age = "unknown"
... @star_property
... def age():
... def fget(self):
... return self._age
... def fset(self, value):
... self._age = value
... return locals()
...
>>> person = Person()
>>> person.age
'unknown'
>>> person.age = 42
>>> person.age
42
However, that is rather hackish, and I recommend that you stick with the
standard approach given by Dennis and limit the use of property as a
decorator to read-only attributes:
>>> class Forever42(object):
... @property
... def age(self): return 42
...
>>> Forever42().age
42
Peter
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