Jean-Michel Pichavant wrote:
Peter wrote:
Situation: I am subclassing a class which has methods that call other
class methods (and without reading the code of the superclass I am
discovering these by trial and error as I build the subclass - this is
probably why I may have approached the problem from the wrong
viewpoint :-)).
Problem: when overriding one of these "indirectly called" superclass
methods I would like to take differing actions (in the subclass
instance) depending on whether it is the superclass or the subclass
instance performing the call.
Question: Is there any way to determine in a method whether it is
being called by the superclass or by a method of the subclass
instance?
Now I suspect that what I am doing is actually very muddy thinking :-)
and I don't want to attempt to explain why I am approaching the design
this way as an explanation would require too much work - I will
consider an alternative inheritance approach while waiting an answer,
but the answer to the question interested me (even if I do a redesign
and come up with a more "elegant" approach to the problem).
Thanks
Peter
As you suspected, this is probably the wrong approach.
However since you asked for a solution anyway :o)
class Parent(object):
def foo(self):
# implementation by subclasses is still REQUIRED
if self.__class__ is Parent:
raise NotImplementedError()
# common code for all foo methods
print "calling foo"
class Child(Parent):
def foo(self):
# You can still call the virtual method which contains some code
Parent.foo(self)
# here the custom code
p = Parent()
c = Child()
c.foo()
p.foo()
Note that this is not the best approach, still acceptable because
there is no code specific to a subclass in the base class.
JM
I just realized I didn't addressed the problem you described, sorry,
just ignore my mail.
JM
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