Re: inheritance
Hello Ian, Ian Kelly writes: > On Thu, Apr 5, 2012 at 10:50 AM, yag wrote: >> three classes A,B,C and instance x. >> >> now how can I call methods foo in class A and B using 'x' instance. (I hope I >> could pronounce the terminology correct) > > Do you mean that you want C.foo to call B.foo, and B.foo to call > A.foo? If that is the case, just use super(), as you already do with > the __init__ method. > > Or do you want to skip C.foo and call A.foo or B.foo directly? yes! >In that case, just call it from the specific class you want. Since you > are dispatching from the class instead of the instance, I couldn't understand what you mean here, (may be because my poor knowledge with the terminology) >you will have > to pass the instance in explicitly as the self argument. For example: > B.foo(x) # calls B.foo directly with instance x This is interesting, Now I kind of vaguely getting why we keep 'self' argument around in each method. Thanks you -- YYR -- http://mail.python.org/mailman/listinfo/python-list
Re: inheritance
Hello Ian, Yagnesh Raghava Yakkala writes: > Hello Ian, > > Ian Kelly writes: [snipped 21 lines] > >>you will have >> to pass the instance in explicitly as the self argument. For example: > >> B.foo(x) # calls B.foo directly with instance x After follow up, I see one problem(can i say that?) with this. With python overwriting methods of super class(es), one need to keep track of all the methods ever defined in the super class(es). do everybody do a check before writing a new method for existing method with the same name.? -- YYR -- http://mail.python.org/mailman/listinfo/python-list
Re: inheritance
Hello Chris, Chris Angelico writes: > > If you're subclassing something, you should generally work with the > intention that an instance of your class will function viably in any > situation in which an instance of the parent is wanted. So if you're > writing a method of the same name as one in the parent, you should be > performing the exact same task and with the same parameters (possibly > having more parameters accepted, but default values set for them). > That's part of what it means to subclass. Thanks for explaining. It makes sense. I see that python interpreter can instantly tell the list of defined methods in the super class(es). So "keeping track" thing is not at all a problem. Thanks a lot again. -- YYR -- http://mail.python.org/mailman/listinfo/python-list
[solved] Re: inheritance
Hello,
With Chris and Ian help (Thank you both)
I end up writing the example script like this,(just for the record)
-
#! /usr/bin/env python3
# -*- coding: utf-8 -*-
class A(object):
def __init__(self, a):
print('a = ', a)
self.a = a
def foo(self):
print('printing from foo in A = ',self.a)
class B(A):
def __init__(self, b, a):
super(B, self).__init__(a)
print('b = ', b)
self.b = b
def foo(self):
print('printing from foo in B = ',self.b)
def bar(self):
print('printing from foo in B = ',self.b)
class C(B):
def __init__(self, c, b, a):
super(C, self).__init__(b, a)
print('c = ', c)
self.c = c
def foo(self):
print('printing from foo in C = ',self.c)
def baz(self):
print('printing from foo in C = ',self.c)
x = C(3,2,1)
x.bar()
x.baz()
print("")
x.foo()
B.foo(x)
A.foo(x)
# inheritance.py ends here
-
--
YYR
--
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