API design question: use methods or properties?

[buran]

use @property decorator

class Foo:
    @property
    def size(self):
        return 42

foo = Foo()
print(foo.size)
foo.size = 32

output

42
Traceback (most recent call last):
  File "/home/boyan/sandbox2/forum.py", line 34, in <module>
    foo.size = 32
AttributeError: can't set attribute