An implementation of Python properties akin to Python property() built-in for the purpose of showing descriptors. It has some limitations: 1) it doesn't implement the del operation 2) decorator syntax can only be used for read-only properties. Example usage is included (see Foo class below). Read the full article: http://daviderizzo.com/2013/05/…

property.py

class PythonProperty(object):
    """
    A property-like descriptor written in Python.

    Simplifications from built-in property():
    - it doesn't implement the del operation
    - decorator syntax can only be used for read-only properties
    """

    def __init__(self, getter, setter=None):
        # We need a function for the getter and one for the
        # setter. setter could be None, in which case we
        # would have a read-only property.
        self._getter = getter
        self._setter = setter

    def __get__(self, instance, ownertype):
        if instance:
            # descriptor invoked from an instance
            return self._getter(instance)
        else:
            # descriptor invoked from the owner class itself
            return self

    def __set__(self, instance, value):
        if self._setter:
            self._setter(instance, value)
        else:
            raise AttributeError('attribute is read-only')


class Foo(object):
    # a read-only property
    @PythonProperty
    def trout(self):
        return 'blub'

    # a read-write property
    def get_something(self):
        """getter function"""
        return self._something

    def set_something(self, value):
        self._something = value

    something = PythonProperty(get_something, set_something)