属性设置器在Python中给出错误

Question

I am new to Python. I am try to learn the @property decorator in Python. Here is my code:

#!/usr/bin/python
# -*- coding: utf-8 -*-

class C(object):
    """docstring for C"""
    def __init__(self, foo):
        self._foo = foo

    @property
    def foo(self):
        return self._foo
    @foo.setter
    def foo(self, value):
        self._foo = value

        return self.foo


c = C(1)

print c.foo

print c.foo(2)

In the above code first print gave me "1". When I try to set the value to foo, it gives the below error:

Traceback (most recent call last):
  File "sub.py", line 23, in <module>
    print c.foo(2)
TypeError: 'int' object is not callable

How to solve this error. What's wrong my code?

Answer 1

A setter is used with the assignment operator = :

c.foo = 2

A further example how c.foo(2) works:

In [7]: c = C(lambda x: x*x)

In [8]: c.foo(2)
Out[8]: 4

c.foo(…) first gets the value in c.foo , then invokes the function.

Answer 2

Did you mean to do

c.foo = 2

You use properties like you would attributes.