[Dune] Returning Geometries As Objects

[Oliver Sander]

Hi Martin,

>
> as far as I understood Christian, he wants the lifetime (I mean the time
> in which the geometry remains valid) to be unlimited before the next
> release. Changing the user code to call geometry only once (which would
> be wise anyway) might take a lot of time and,

This does not convince me, because a) I think the number of users that 
are as keen
on top assembly speed as you are is not very big b) in standard assembly 
routines
you usually acquire the geometry only once anyways c) until I hear numbers
no speed-loss argument is going to convince me anyways.

I know speed matters a great deal to your group, but I don't think you
guys are representative for the greater Dune community.

Cheers,
Oliver

>therefore, I think a
> longer transition period would be good.
>
> Moreover, I'm still not sure on the correct path. I see at least three
> possibilities:
>
> A geometry object is valid
> (a) for ever (i.e., as long as it exists)
> (b) as long as the grid, the entity belongs to
> (c) as long as the entity exists within the grid
> (d) as long as the corresponding entity pointer is valid (current
> situation)
>
> I think we should at least prescribe (c), so that, e.g., references to
> the corners are allowed.
>
> So: What kind of limit on the lifetime of a geometry do you have in mind?
>
> Best,
>
> Martin
>
>
>
> On 02/07/2012 11:56 AM, Oliver Sander wrote:
>> This pretty much exactly reflects my view. I don't think I want the
>> reference feature in there either. A variable that looks like an
>> object but is in fact a reference is a big violation of the principle
>> of least surprise. To me, the difficult-to-find bugs that lurk here
>> are far more serious than potential speed loss.
>>
>> Concerning the speed loss: are the measurements of how much loss to
>> expect? And can that not be mitigated in the calling code by making
>> sure to call each geometry-Method only once?
>>
>> best,
>> Oliver
>>
>>>
>>> I'm against a merge, unless we agree to disable the reference feature
>>> before the next release. Yes, this will require updates in all grid
>>> implementations, but I think it is necessary to make this change show
>>> its full potential and to actually value all the work and time you
>>> spent here.
>>>
>>> If we can agree on this, I have no furthe objections regarding a
>>> merge. I think it is well enough tested to actually do a merge. My
>>> main concern is about adding undesired features which we (might) have
>>> to deal with for an unforseable time.
>>>
>>> And "we agree" does not necessarily require a formal vote. I think it
>>> just means that those people involved in (core) grid implementations
>>> have to agree. I, for my part, am willing to do add the necessary
>>> changes. Now we only need an opinion from Robert and Oliver [assuming
>>> that you actually want to use you new feature ;-)].
>>>
>>> Cheers
>>> Christian
>>>
>>>
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>>
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