OOP / language design question

[Carl Banks]

cctv.star at gmail.com wrote:
> Heiko Wundram wrote:
> > Because sometimes you don't want to call the base classes constructors?
> Sounds strange to me at the moment, but I'll try to adjust to this
> thought.

In Java and C++, classes have private members that can only be accessed
by the class itself (and, in C++, friends).  In those languages, a base
constructor needs to be called to initialize the base class's private
members.

Python has no private members (except for the double underscore
thingies, which aren't that common).  Unlike C++ and Java, the derived
class's __init__ can usually initialize all the base class's members,
and it's occasionally useful to do so.

I would agree it's a mistake to not call the base class's __init__
unless you're doing it deliberately.  If you want a tool to catch those
mistakes, have a look at pychecker.  It can inform you whenever the
base class __init__ is not called.

(However, I totally disagree that it's a good idea to always call it
first, though.  I've written base class __init__s that expected the
subclass to provide initialization methods, and some of those methods
needed some subclass members to exist before they were called.)