Cannot access member variable using abc module and properties in python

Question

I wrote a code that simulates the use of abc module and properties. However, it seems that I couldn't be able to access width and height variables. The code is as the following:

from abc import ABCMeta, abstractmethod

class Polygon:

__metaclass__ = ABCMeta

@abstractmethod
def compute_area(self): pass


def __init__(self):
    self.width = None
    self.height = None

@property
def width_prop(self):
    return self.width

@property
def height_prop(self):
    return self.height

@width_setter.setter
def width_setter(self, width):
    self.width = width

@height_setter.setter
def height_setter(self, height):
    self.height = height



class Triangle(Polygon):
    def compute_area(self):
        return 0.5 * width * height




if __name__ == "__main__":
    tri = Triangle()
    tri.height_setter(20)
    tri.width_setter(30)
    print "Area of the triangle = ", tri.compute_area()

The error message that I obtained is NameError: name 'width_setter' is not defined. What could be wrong in my implementation?

EDIT:

from abc import ABCMeta, abstractmethod

class Polygon:

__metaclass__ = ABCMeta

@abstractmethod
def compute_area(self): pass


def __init__(self):
    self.width = None
    self.height = None

@property
def width_prop(self):
    return self.width

@width_prop.setter
def width_setter(self, width):
    self.width = width

@property
def height_prop(self):
    return self.height

@height_prop.setter
def height_setter(self, height):
    self.height = height



class Triangle(Polygon):
    def compute_area(self):
        return 0.5 * self.width * self.height




if __name__ == "__main__":
    tri = Triangle()
    tri.height_prop = 20
    tri.width_prop = 30
    print "Area of the triangle = ", tri.compute_area()

Answer 1

edit: In such simple case like example use direct variable access. See Ned Batchelder's answer.

If you need extra functionality when accessing variables you can use this.

---

http://docs.python.org/library/functions.html#property

from abc import ABCMeta, abstractmethod

class Polygon(object):

    __metaclass__ = ABCMeta

    @abstractmethod
    def compute_area(self): 
        pass


    def __init__(self):
        self._width = None
        self._height = None

    @property
    def width(self):
        getting_variable_value()
        return self._width

    @width.setter
    def width(self, width):
        setting_variable_value()
        self._width = width

    @property
    def height(self):
        getting_variable_value()
        return self._height

    @height.setter
    def height(self, height):
        setting_variable_value()
        self._height = height



class Triangle(Polygon):
    def compute_area(self):
        return 0.5 * self.width * self.height


if __name__ == "__main__":
    tri = Triangle()
    tri.height = 20
    tri.width = 30
    print "Area of the triangle = ", tri.compute_area()