I believe that the answer to my question is no, but I want to be sure that I
understand this issue correctly: Suppose that there are two classes
defined as follows:
class A(object):
def f1(self):
print 'In A.f1, calling func'
self.func()
def func(self):
print 'In A.func'
class B(A):
def func(self):
print 'In B.func, calling A.f1'
A.f1(self)
Class A was defined by someone else or it comes from a library, so I have no
prior information about what is in it. I subclass A to add some new
functionality, and I call the new function "func". The function B.func
uses A.f1, but unbeknownst to me, A.f1 uses A.func. Unfortunately, class B
overrides func, so the call in A.f1 to self.func actually invokes B.func,
resulting in this case in an infinite loop. Is there a way from B to
specify that A should use its own version of func and ignore the version in
B? I know that I could rename A.func to avoid the name clash, but since A
is actually in a library, I will lose that change when I upgrade the
library. I could rename B.func, but there is already a bunch of code that
calls it so I would have to update all the calls. That seems like the
correct solution, though. The other possibility is to use composition
rather than subclassing:
class B:
def func(self):
print 'In B.func, calling A.f1'
a = A()
a.f1()
but then B does not inherit other functions of A that I would like to use.
It struck me that this must be a common problem in OOP, so I'm wondering
whether there is a simple solution that I am missing.
--
Jeffrey Barish
--
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