On 2/17/2010 8:53 AM, mk wrote:
Found in Dive into Python:
"""Guido, the original author of Python, explains method overriding this
way: "Derived classes may override methods of their base classes.
Because methods have no special privileges when calling other methods of
the same object, a method of a base class that calls another method
defined in the same base class, may in fact end up calling a method of a
derived class that overrides it. (For C++ programmers: all methods in
Python are effectively virtual.)" """
So, I set out to create such case:
class A(object):
def __init__(self):
print "A"
def met(self):
print "I'm A's method"
def overriden(self):
print "I'm A's method to be overriden"
def calling_overriden(self):
self.overriden()
class B(object):
def __init__(self):
print "B"
def met(self):
print "I'm B's method"
class C(A):
def __init__(self, arg):
print "C","arg=",arg
A.__init__(self)
def met(self):
print "I'm C's method"
class D(B):
def __init__(self, arg):
print "D", "arg=",arg
B.__init__(self)
def met(self):
print "I'm D's method"
class E(C,D):
def __init__(self, arg):
print "E", "arg=",arg
C.__init__(self, arg)
D.__init__(self, arg)
def some(self):
self.met()
def overriden(self):
print "I'm really E's method"
e = E(10)
print 'MRO:', ' '.join([c.__name__ for c in E.__mro__])
e.some()
e.calling_overriden()
Result:
...
MRO: E C A D B object
I'm C's method
I'm really E's method
Is what I concocted in e.calling_overriden() == what Guido said on base
class sometimes calling overriden method instead of its own original
method?
Much more complicated than needed for this point, but I believe yes.
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