list extension ?
bruno.42.desthuilliers at websiteburo.invalid
Mon Jun 30 12:08:58 CEST 2008
Stef Mientki a écrit :
> 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 )
> # and with this new list component, I can add new attributes on the fly
> a = tGrid_list ( [ 2, 3 ] )
a = GridList(2, 3)
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
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