Question

I don’t know when an attribute should be private and whether I should use property.

I read recently that setters and getters are not pythonic but using the property decorator is OK.

But what if I have attribute, that mustn’t be set from outside of class but can be read (read-only attribute). Should this attribute be private, and by private I mean with underscore, like that self._x?
If yes, then how can I read it without using getter?
Only method I know right now is to write

@property
def x(self):
    return self._x

That way I can read attribute by obj.x but I can’t set it obj.x = 1 so it’s fine.

But should I really care about setting object that mustn’t be set? Maybe I should just leave it. But then again I can’t use underscore because reading obj._x is odd for user, so I should use obj.x and then again user doesn’t know that he mustn’t set this attribute.

What’s your opinion and practices?

Answer 1

Generally, Python programs should be written with the assumption that all users are consenting adults, and thus are responsible for using things correctly themselves. However, in the rare instance where it just does not make sense for an attribute to be settable (such as a derived value, or a value read from some static datasource), the getter-only property is generally the preferred pattern.