Re: [Configobj-develop] Ordered Dictionary, keys and values

[Nicola L. <ni...@te...>]

[Sorry for the lateness, it's been a busy week, and it's not over yet.]


> What about this suggestion. It sounds a little esoteric to me - but if
> you think it's worth the effort I'll do it.

I am not sure I understand it (did not yet read the whole comp.lang.python
thread). Can you give a few usage examples?


> We could implement the ``keys`` and ``values`` methods as custom objects
> with all the sequence methods. (With error checking so you can't mutate
> the keys so that they don't reflect the internal contents of the odict).

Do you mean that the ``keys`` and ``values`` methods *return* custom objects?


> We would also implement ``__getitem__``, ``__setitem__``, and
> ``__call__`` such that you can directly index (slice, delete, etc)
> members as if it was a list.

Do you mean as these?

k4 = d1.keys()[4]
d1.values()[4] = v4


> You can also call it as if it was a method
> - including passing it a sequence to replace the current keys with.
> 
> We would presumably have to implement ``__setattr__`` on the main
> OrderedDict so that :
> 
> d1 = OrderedDict(sequence_of_tuples)
> d1.keys = a_list
> 
> is the same as :
> 
> d1 = OrderedDict(sequence_of_tuples)
> d1.keys(a_list)

If the two forms are equivalent, I'd say just do the first...

> What should ``d1.keys(a_list)`` return ? (The same as d1.keys() I guess
> - except with the new key set).

...so that we dodge this question. :-)


> We (I) would still implement slicing, insert, reverse, and sort for the
> OrderedDict class itself.

What is there to sort? Isn't it already sorted? :-)


> Fredrik Lundh pointed out the performance impact of adding to many
> layers above the C implementation. I have no idea how relevant that is
> to the suggestion I've just made. :-) (How many method calls would
> indexing or assigning to the ``keys`` object actually result in 'under
> the hood' ?)

I'm not sure I grasp the last sentence. Performance is good, and I
generally like *some* optimization, but in this context convenience and
versatility, without excess, do override performance concerns.

-- 
Nicola Larosa - ni...@te...

She was up the learning curve like a mountain goat.
 -- WasterDave on Slashdot, October 2005