Classes and Python

Aahz Maruch aahz at panix.com
Thu Jan 24 17:34:28 CET 2002


In article <2jc05usg0sic5f9evcdfsa9jebecvkmb93 at 4ax.com>,
Lawrence Oluyede  <rhymes at myself.com> wrote:
>
>I'm a newbie of Python and I'm still reading its tutorial (downloaded
>from the official site).
>
>I've found this sentence:
>
>I also have to warn you that there's a terminological pitfall for
>object-oriented readers: the word ``object'' in Python does not
>necessarily mean a class instance. Like C++ and Modula-3, and unlike
>Smalltalk, not all types in Python are classes: the basic built-in
>types like integers and lists are not, and even somewhat more exotic
>types like files aren't. However, all Python types share a little bit
>of common semantics that is best described by using the word object. 
>
>What's the real meaning of that?

The real meaning is that if you're using the current Python 2.2, it's
wrong.  ;-)

But it's probably still worthwhile to explain it:

Let's suppose you create a list with

>>> L=[]
>>> L
[]

now you can add a new element to L with

>>> L.append('foo')
>>> L
['foo']

this means that L has object-like behavior, in that there are methods
that can be used.  But you cannot subclass from the list type in
versions of Python prior to 2.2 -- this is called the type/class split.
Python 2.2 takes the first steps to heal the type/class split, and you
*can* now inherit from the list type.
-- 
                      --- Aahz  <*>  (Copyright 2002 by aahz at pobox.com)

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