Python meta object question

[Arpad Kiss]

----- Original Message -----
From: Mickael Remond <mikl at linux-france.org>
Newsgroups: comp.lang.python
To: <python-list at python.org>
Sent: Wednesday, December 01, 1999 7:29 AM
Subject: Re: Python meta object question


> Mickael Remond wrote:
> >
> > Hello,
> >
> > Is there a way to automatically update the class tree to show the change
> > in inherited class attributes after a class redefinition ?
> >
>
> [...]
>
> In fact, this example was an attempt at using meta programming features
> of python.
>
> In a Bytes Magazine article (1997) I read that :
>
>      For a programming language, Python is flexible. Classes and method
>      refer ences in Python are treated as first-class objects. That is,
>      new methods and member variables can be added to a class at any
>      time, and all existing and future instances of classes are affected
>      by these changes. This way, a scheduled event on a server program
>      can change a variable in the class definition that defines each
>      user's privileges. Thus, when standard office hours end, access
>      could be broadened automatically to certain users with a single
>      line of code such as userClass.restrictions=3 . All existing and
>      future instances of userClass are updated and use this new value
>      until the class variable is changed again. A programmer maintaining
>      the code for the server could log in and be allowed to add or
>      update classes and methods without having to take the server down.
>
> I did not find any clue on how to leverage these features. Are they out
> of date ?

Well, I use member variables this way:

>>> class a:
...   ca="dog"
...   def __init__(self,name):
...    self.name=name
...
>>> mydog=a("tibi")
>>> mydog.ca, mydog.name
('dog', 'tibi')
>>> a.ca="cat"
>>> mydog.ca, mydog.name
('cat', 'tibi')

Arpad

>
> Mickael Remond
>