Examples - Subclassing

Simple subclassing example

from java.util import ArrayList

class CountingArrayList(ArrayList):
  def __init__(self):
    ArrayList.__init__(self)
    self.count = 0L

  def get(self, index):
    self.count += 1
    return ArrayList.get(self, index)

a = CountingArrayList()
a.add(1)
a.add(1)
a.add(2)
a.add(3)
a.add(5)

print "len says: %02d, size says: %02d" % (len(a), a.size())

a.get(0)
a.get(4)

print "accessed %02d times" % (a.count)

ex_subclass.py

Collections are proxied so __len__ and other magic methods work as expected (most of the time).