property

from datetime import datetime

class Person(object):
    def __init__(self, born):
        self.born = born

    @property
    def age(self):
        return self.__age

    #def age(self):
        #return self.__age
    #age = property(age)

    def _get_born(self):
        return self.__born

    def _set_born(self, born):
        self.__born = born
        self.__age = (datetime.now().year - born.year)

    born = property(_get_born, _set_born)


>>> person = Person(datetime(1954, 1, 25))
>>> person.born
datetime.datetime(1954, 1, 25, 0, 0)
>>> person.age
54
>>> person.born = datetime(1968, 8, 31)
>>> person.age
40
>>> person.age = 16
---------------------------------------------------------------------------
<type 'exceptions.AttributeError'>        Traceback (most recent call last)

C:\Documents and Settings\murkt\<ipython console> in <module>()

<type 'exceptions.AttributeError'>: can't set attribute





class C(object):
  def __init__(self, x):
    self.x = x

obj = C(5)
obj.x = 6    # set
print obj.x  # get






class C(object):
  def __init__(self, x):
    self._x = x

  def get_x(self):
    return self._x
  def set_x(self, x):
    self._x = x
  x = property(get_x, set_x)

obj = C(5)
obj.x = 6    # set
print obj.x  # get



>>> print property.__doc__
property(fget=None, fset=None, fdel=None, doc=None) -> property
attribute


class C(object):
    def getx(self): return self.__x
    def setx(self, value): self.__x = value
    def delx(self): del self.__x
    x = property(getx, setx, delx, "I'm the 'x' property.")



import math
 
class triang(object):
 
        sidea=0
        sideb=0
        sidec=0
 
        def __init__(self,a,b,c):
                self.sidea = a
                self.sideb = b
                self.sidec = c
 
        def getArea(self):
                s = 0.5 * (self.sidea + self.sideb + self.sidec)
                ta = math.sqrt(s*(s-self.sidea)*(s-self.sideb)*(s-self.sidec))
                return ta
 
        def setArea(self,value):
                s = 0.5 * (self.sidea + self.sideb + self.sidec)
                raise AttributeError, "Area cannot be altered"

#http://users.rcn.com/python/download/Descriptor.htm