On 04/18/2017 04:00 AM, Thomas Güttler wrote:
> I would like to have read-only class properties in Python.
>
> I found this
> http://stackoverflow.com/questions/128573/using-property-on-classmethods
> But there are a lot of discussions of things which I don't understand.
>
> I want to be a user of class properties, not an implementer of the details.
>
> I found this: https://pypi.python.org/pypi/classproperty
>
> But above release is more then ten years old. I am unsure if it's dead
> or mature.
>
> I am using Python 2.7 and attribute getters would be enough, no
> attribute setter is needed.
>
> My use case is configuration, not fancy algorithms or loops.
>
> Regards,
> Thomas Güttler
>
Not clear if you're asking for something more than the standard Python
properties. The discussion you mention does go into additional
discussion which describes techniques for applying this to a class
attribute. In other words, is this quote a problem for you?
"The get method [of a property] won't be called when the property is
accessed as a class attribute (C.x) instead of as an instance attribute
(C().x). "
If applying to instance attributes is fine for your case, then the
property() call or the related decorators should do the trick, as in:
def get_temperature(self):
return self._temperature
def set_temperature(self, value):
self._temperature = value
temperature = property(get_temperature,set_temperature)
or, as is probably preferred:
@property
def temperature(self):
return self._temperature
@temperature.setter
def temperature(self, value):
self._temperature = value
(obviously both a getter and setter)
Note it's Python convention to use an underscore-prefixed variable name
to indicate it is "private", and you often see a backing store for the
property written like I did above, but nothing in Python enforces this
privacy, someone could fiddle directly with instance._temperature
Also ask yourself whether you really _need_ a property here? Or would a
public data member be sufficient. (Just asking, have no idea what's
inside your use case)
_______________________________________________
Tutor maillist - Tutor@python.org
To unsubscribe or change subscription options:
https://mail.python.org/mailman/listinfo/tutor
