#!/usr/bin/env python
# This is a doctest
"""
=========================================
Subclassing Objective-C classes in Python
=========================================
It is possible to subclass any existing Objective-C class in python.
We start by importing the interface to the Objective-C runtime, although
you'd normally use wrappers for the various frameworks, and then locate
the class we'd like to subclass::
>>> import objc
>>> NSEnumerator = objc.lookUpClass('NSEnumerator')
>>> NSEnumerator
<objective-c class NSEnumerator at 0xa0a039a8>
You can then define a subclass of this class using the usual syntax::
>>> class MyEnumerator (NSEnumerator):
... __slots__ = ('cnt',)
... #
... # Start of the method definitions:
... def init(self):
... self.cnt = 10
... return self
... #
... def nextObject(self):
... if self.cnt == 0:
... return None
... self.cnt -= 1
... return self.cnt
... #
... def __del__(self):
... global DEALLOC_COUNT
... DEALLOC_COUNT = DEALLOC_COUNT + 1
To check that our instances our deallocated we maintain a ``DEALLOC_COUNT``::
>>> DEALLOC_COUNT=0
As always, the creation of instances of Objective-C classes looks a bit odd
for Python programs:
>>> obj = MyEnumerator.alloc().init()
>>> obj.allObjects()
(9, 8, 7, 6, 5, 4, 3, 2, 1, 0)
Destroy our reference to the object, to check if it will be deallocated::
>>> del obj
>>> DEALLOC_COUNT
1
"""
import doctest
import __main__
doctest.testmod(__main__, verbose=1)
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