For about the third time in my life, I thought I might
have found a use for cooperative super calls, but I've
run into another problem with the concept.
Consider:
class A(object):
def m(self):
print "A.m"
class B(object):
def m(self):
print "B.m"
super(B, self).m()
class C(B, A):
def m(self):
print "C.m"
super(C, self).m()
>>> c = C()
>>> c.m()
C.m
B.m
A.m
Okay so far, but... what if I want to use class B on
its own, or in combination with other classes that don't
have an m() method?
>>> b = B()
>>> b.m()
B.m
Traceback (most recent call last):
File "<stdin>", line 1, in ?
File "<stdin>", line 4, in m
AttributeError: 'super' object has no attribute 'm'
In general, how is one supposed to use super() in a
class which may or may not be at the end of the mro
with respect to a particular method?
The only thing I can think of is to write all my
super()-using methods defensively like this:
def m(self):
...
s = super(C, self)
if hasattr(s, 'm'):
s.m()
which seems awfully tedious.
Does the Theory of Cooperative Method Calls have
anything to say about this?
--
Greg
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