pythius-developers

[Pythius-developers] setattr and list.append()

[Adrien Di M. <Adr...@lo...>]

Hi all,

I'm pretty new in AOP, and I'm looking for all kind of AOP-related stuff
for Python. I found Pythius, and I'm trying to use the Logger aspect in
a small program.
It seems to work fine, but I had a small problem.
I would like to add some log-events when a list is modified.

Suppose I have :

#####################################
class A:
    __metaclass__ = aop.Metaclass
    _aspect = my_logger()

    def __init__(self):
        self.l = []
    ...
#####################################

What I would like to do is to check when "self.l" is changed
(self.l.append() or self.l.pop() or ...) . I tried
to add a "self.before('setattr', 'l', self.list_changed)" but it didn't
work.

How could I do what I'm trying to do ?

This may be a basic problem, but I'm a newbie with all this stuff.

Cheers,

Adrien.
--
Adrien Di Mascio
LOGILAB, Paris (France).
http://www.logilab.com   http://www.logilab.fr   http://www.logilab.org

[Pythius-developers] Re: setattr and list.append()

[Frank T. <ft...@ne...>]

Adrien Di Mascio, on 2003-02-26, wrote:

> What I would like to do is to check when "self.l" is changed
> (self.l.append() or self.l.pop() or ...) . I tried to add a
> "self.before('setattr', 'l', self.list_changed)" but it didn't work.

A 'setattr' of attribute L on object O is not the same as that attribute
'changing', e.g., by o.l.append(), o.l.pop().

I think the only way you could approach the problem you want to solve with
Pythius is to have the L attribute itself (and not its 'holder')  
subclass the class 'list' and be the 'aspectified' object and have a bunch
of statements that cover each 'modifying' method such as:

self.after('method_call', 'pop',    self.i_changed) 
self.after('method_call', 'append', self.i_changed)

Other than that, there's no real way for the 'holder' of L to know that an
attribute of itself has changed values, especially if you started doing
things like:

l2 = o.l
l2.append('foo')  # this changed o.l

Sorry that's there's no easy answer to your question :(

-- 
Frank Tobin			http://www.neverending.org/~ftobin/