CODEWITHSUNDEEP
pythonclassproperties
mart1n
mart1n

Reputation: 6213

Python: modifying property value

I have the following code that uses two simple properties:

class Text(object):

    @property
    def color(self):
        return 'blue'

    @property
    def length(self):
        return 22

t = Text()
print t.color

When I run this, it obviously returns blue. But how can I update the value of color on the fly later in the code? I.e. when I try to do:

t = Text()
print t.color
t.color = 'red'
print t.color

It fails with a can't set attribute error. Is there a way to modify the value of a property?

EDIT:

If the above code is rewritten to use setters as in williamtroup's answer, what is the advantage of simply shortening it to:

class Text(object):

    def __init__(self):
        self.color = self.add_color()
        self.length = self.add_length()

    def add_color(self):
        return 'blue'

    def add_length(self):
        return 22

Upvotes: 6

Views: 18723

Answers (1)

William Troup
William Troup

Reputation: 13131

You need a setter for the property and a class variable to store the data.

With your example:

class Text(object):

    def __init__(self):
        self._color = "blue"
        self._length = 12

    @property
    def color(self):
        return self._color

    @color.setter
    def color(self, value):
        self._color = value

    @property
    def length(self):
        return self._length

    @length.setter
    def length(self, value):
        self._length = value

Upvotes: 8

Related Questions