I like the idea proposed in https://trac.sagemath.org/ticket/29101 (as
posted by Matthias). Namely, introducing the option mutable=False for the
element constructor. Then your code could be rewritten to
sum( D[V(v0+w, mutable=False)] for w in W)
which should be fine, I guess.
Travis Scrimshaw schrieb am Montag, 9. August 2021 um 07:14:41 UTC+2:
> I think Nils' original solution, of adding an immutable keyword option to
>> the parent, is a good one. I've run into a similar issue with matrices,
>> where I had to make them immutable before using them as dictionary keys.
>>
>
> I also ran into this when implementing Lie algebras over matrices. I had
> to do special casing and subclasses to get around the mutability that
> doesn't exist for other classes in Sage. I would like to see some way of
> working with immutable matrices/vectors. (Internally, we need to mutate
> stuff in place for efficiency, such as in echelonize(). However, I believe
> we are all in agreement about still supporting mutable matrices/vectors.)
>
> Best,
> Travis
>
>
>>
>>
>
>> On Fri, Aug 6, 2021 at 7:39 PM Nils Bruin <nbr...@sfu.ca> wrote:
>>
>>> On Friday, 6 August 2021 at 16:31:23 UTC-7 wst...@gmail.com wrote:
>>>
>>>> To clarify, by "similar reasons to numpy", I meant that you open up
>>>> the possibility of using Cython, vectorized operations, JITs like
>>>> numba, etc. Some of these provide order of magnitude speedups and
>>>> aren't an option with generic Python lists.
>>>
>>>
>>> To clarify, this thread certainly didn't start out with the question if
>>> sage should have mutable vectors at all (although I do think that in most
>>> cases, an array would then work just as well). I think it is worth
>>> reconsidering whether all vectors need to start out their life being
>>> mutable, because that does come with a significant usability penalty in
>>> hash-related scenarios.
>>>
>>> It is indeed the case that we could just spell these examples as
>>> {tuple(v+w): ... }, and probably that is what cached_function argument
>>> manglers do, but .... to me that just looks super ugly (and the annoying
>>> part is that it'll take me a error for every time I need to insert that).
>>>
>>> --
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