Consider the following:
#!/usr/bin/python
#-----------------------------------------------------------------
class Grand_parent( object ):
def speak( self ):
print 'Grand_parent.speak()'
self.advise()
def advise( self ):
print 'Grand_parent.advise()'
self.critique()
def critique( self ):
print 'Grand_parent.critique()'
#-----------------------------------------------------------------
class Parent( Grand_parent ):
def speak( self ):
print '\tParent.speak()'
self.advise()
def advise( self ):
print '\tParent.advise()'
self.critique()
# ATM, the Parent is at a loss for words, and has no critique.
#-----------------------------------------------------------------
class Child( Parent ):
def speak( self ):
print '\t\tChild.speak()'
self.advise()
# Currently, the Child has no really useful advice to give.
def critique( self ):
print '\t\tChild.critique()'
#-----------------------------------------------------------------
print 'speak() calls advise(), then advise() calls critique().'
print
people = [ Grand_parent(), Parent(), Child() ]
for person in people:
person.speak()
print
====================
The output is:
speak() calls advise(), then advise() calls critique().
Grand_parent.speak()
Grand_parent.advise()
Grand_parent.critique()
Parent.speak()
Parent.advise()
Grand_parent.critique()
Child.speak()
Parent.advise()
Child.critique()
What's going on here with that last "Child.critique()"? The
Parent called self.critique(), and since it *had* no critique()
method, it should've deferred to it's parent's critique()
method, right? But instead, somehow Child.critique() got called.
Why?
---J
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