Anthra Norell wrote:
> Would anyone who knows the inner workings volunteer to clarify whether
> or not every additional derivation of a class hierarchy adds an
> indirection to the base class's method calls and attribute read-writes.
> In C++, I suppose, a three-level inheritance would resolve into
> something like *(*(*(*(base_class_method ())))).
I think in C++ the compiler can often resolve the correct class statically.
Python currently walks through the entire hierarchy.
$ cat inherit.py
class A(object):
def m(self):
return 42
B = A
for i in range(1000):
class B(B): pass
a = A()
b = B()
if __name__ == "__main__":
print a.m()
print b.m()
$ python -m timeit -s"from inherit import a" "a.m"
10000000 loops, best of 3: 0.173 usec per loop
$ python -m timeit -s"from inherit import b" "b.m"
10000 loops, best of 3: 68.7 usec per loop
Peter
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