@kurner/Circle Magic

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• main.py
main.py
```# -*- coding: utf-8 -*-
"""
Created on Thu Oct 20 15:43:14 2016

@author: Kirby Urner

toggle the import model_property on and off to see
the example works the same either way.  model_property
contains a pure Python emulator of the built in
property type.

Related reading:
https://mail.python.org/pipermail/edu-sig/2016-October/011548.html
"""

# from model_property import Property as property
import math

class Circle:
"""setting either the radius or area attribute sets the other
as a dependent value.  Initialized with radius only, unit
circle by default.
"""

def __init__(self, radius = 1):
self.radius = radius

@property
def area(self):
return self._area

@property
def radius(self):
return self._radius

@property
def circumference(self):
return self._circum

@circumference.setter
def circumference(self, value):
self.radius = value / (2 * math.pi)

@area.setter
def area(self, value):
self._area = value
self._radius = math.sqrt(self._area / math.pi)
self._circum = 2 * math.pi * self._radius

@radius.setter
def radius(self, value):
self._radius = value
self._area = math.pi * (self._radius ** 2)
self._circum = 2 * math.pi * self._radius

def __repr__(self):
return "Circle(radius = {})".format(self.radius)

the_circle = Circle(5)
print("the_circle:", the_circle)
print("Area: ", the_circle.area)
the_circle.area = 50
print("Radius when Area=50:", the_circle.radius)```
Python 3.6.1 (default, Dec 2015, 13:05:11) [GCC 4.8.2] on linux