Re: list extension ?

Stef Mientki a écrit :
hello,

I basically need a list with a few extra attributes,
so I derived a new object from a list, and it works perfect.
But I wonder why the newly derived list component is much more flexible ?

# so here is the new list object
class tGrid_List ( list ) :

pep08: class GridList(list):

def __init__ ( self, value = [] ) :

Gotcha : default argument values are eval'd only once. Also, it would make more sense IMHO to follow the parent's class initializer's behaviour:

def __init__(self, *args)

list.__init__ ( self, value )

list.__init__(self, *args)

# and with this new list component, I can add new attributes on the fly

a = tGrid_list ( [ 2, 3 ] )

a = GridList(2, 3)

or
l = [2, 3]
a = GridList(*l)

a.New_Attribute = 'some text'

# I'm not allowed to this with the standard list

a = [ 2, 3 ]
a.New_Attribute = 'some text' <== ERROR

Can someone explain this different behavior ?

Most builtin types are optimized, and not having a __dict__ is part of this optimization.
.