dictionary with order?

[York]

Hi, everybody

The dictionary in python add a new method -- "setdefault", that is very 
useful.
Usually items in a python dictionary have no order:
>>> d = {}
>>> d[1] = 1
>>> d[2] = 2
>>> d
{1: 1, 2: 2}
>>> d["a"]="a"
>>> d
{'a': 'a', 1: 1, 2: 2}
>>> d["b"]="b"
>>> d
{'a': 'a', 1: 1, 2: 2, 'b': 'b'}
>>> d.keys()
['a', 1, 2, 'b']
>>> d.items()
[('a', 'a'), (1, 1), (2, 2), ('b', 'b')]

But sometimes I need keys() return the sequence:
[1, 2, "a", "b"], or items() return
[(1, 1), (2, 2), ("a", "a"), ("b", "b")]

Is it make sense to let a python dictionary arrange its items according to 
the order that an items be added in? 
for example, by add a new method "setorder" (d.setorder(1) or 
d.setorder(-1) for reverse order) to let mothods like keys(), values(), 
items() return sequence with items order same to the order for these items 
be added.

Cheers,
York