Is it possible to implement properties in languages other than C#?

Question

During a bout of C# and WPF recently, I got to like C#'s properties:

public double length_inches
{
    get { return length_metres * 39.0; }
    set { length_metres = value/39.0; }
}

Noticing, of course, that length_metres may change from being a field to a property, and the code need not care. WPF can also bind UI elements to object properties very happily.

When I first learnt about classes and objects, I assumed that there was a way to do it, because it seemed so obvious! The point of hiding complexity inside a class is that you don't need to care what is being stored any more. But it has taken until now to see it.

Amusingly, I first saw it done in VB.Net. That leading edge of OO purity.

The question is, can I recreate properties in other languages which I use more often, like javascript, python, php? In javascript, if I set a variable to a closure, won't I get the closure back again, rather than the result of it?

Answer 1

Python definitely supports properties:

class Foo(object):

    def get_length_inches(self):
        return self.length_meters * 39.0

    def set_length_inches(self, val):
        self.length_meters = val/39.0

    length_inches = property(get_length_inches, set_length_inches)

Starting in Python 2.5, syntactic sugar exists for read-only properties, and in 2.6, writable ones as well:

class Foo(object):

    # 2.5 or later
    @property
    def length_inches(self):
        return self.length_meters * 39.0

    # 2.6 or later
    @length_inches.setter
    def length_inches(self, val):
        self.length_meters = val/39.0

Answer 2

In JavaScript:

var object = {
  // .. other property definitions ...
  get length_inches(){ return this.length_metres * 39.0; },
  set length_inches(value){ this.length_metres = value/39.0; }
};