Question

class ClassName(object):
    """
    """    
    def __init__(self, foo, bar):
        """
        """
        self.foo = foo # read-write property
        self.bar = bar # simple attribute

    def _set_foo(self, value):
        self._foo = value

    def _get_foo(self):
        return self._foo

    foo = property(_get_foo, _set_foo)

a = ClassName(1,2)
#a._set_foo(3)
print a._get_foo()

When I print a._get_foo() the function _get_foo prints the variable self._foo .
But where does it come from?
self._foo and self.foo are different, aren’t they?

EDIT: The problem is that I still not understand what property does. Give me some time.

Answer 1

Docs for property explain how it’s supposed to be used. There is no difference between these lines:

self.foo = foo # read-write property

and

a.foo = 3

You’re also not supposed to call setters and getters manually.

eta: if you don’t understand what property does after looking at the examples provided in the docs and reading our answers, you perhaps should just abstain from using it. It really is not the most essential of Python’s features. You might want to start with a simpler example, which is easy to understand:

>>> class ClassName(object):
    def __init__(self, foo):
        self.foo = foo


>>> a = ClassName(1, 2)
>>> a.foo
1
>>> a.foo = 42
>>> a.foo
42