Initialization of base classes

[Mark McEahern]

[sorry.antispam at address.net]
> On pp 74 of Bealey's excellent book "Python Essential Reference, 2nd
> Ed" it is written:
>
> "When an instance is created [of a derived class], the __init__()
> methods of base classes are not invoked. Thus, it's up to a derived
> class to perform the proper initialization of its base classes, if
> necessary"
>
> Is this really true?

Consider this, though:

>>> class A:
...     def __init__(self):
...             print "A"
...
>>> class B:
...     def __init__(self):
...             print "B"
...
>>> class C(A):
...     def __init__(self):
...             pass
...
>>> class D(A, B):
...     def __init__(self):
...             pass
...
>>> w = A()
A
>>> x = B()
B
>>> y = C()
>>> z = D()

This seems to be the scenario the book is describing:  If the derived class
defines __init__(), the base classes' __init__()s will not get called unless
you call them explicitly.

Cheers,

// mark