Why you should care

Python is not Java. If you need to set or get the members of a class or object, just expose the member publicly and access it directly. If you need to perform some computations before getting or setting the member, then use Python’s built-in property decorator.

Usage of built-in property decorator allow to associate a member access syntax (<object>.<attribute>), to a treatment implemented by a function. this is usefull because:

• there is no “private attribute” concept in python’s classes. But property decorator force getters and setter decorators force to call a getter for each access to a member.
• for existing client code accessing directly to members , it is possible to add data treatment throught getter and setter without needing to modify the client code.

  class P:
      def __init__(self,x):
          self.x = x

      @x.setter
      def x(self, x):
          if x < 0:
              self.__x = 0
          elif x > 1000:
              self.__x = 1000
          else:
              self.__x = x

      @property
      def x(self):
          return self.__x

Business Impacts

CAST recommendations

References

http://docs.quantifiedcode.com/python-code-patterns/correctness/implementing_java-style_getters_and_setters.html