On Wed, 9 Sep 2009, Andrew Whitworth wrote:
> On Wed, Sep 9, 2009 at 9:36 AM, Austin
> Hastings<[email protected]> wrote:
> > Adding ppsu would make PVM "more complete", but it probably wouldn't change
> > the way people are writing PIR - old habits, etc.
>
> The Fixed*Array types allocate a fixed amount of storage. Adding ppsu
> ops to it would require keeping track of not only how much storage we
> have allocated (some of which is possibly empty), but also keeping
> track of where the current "beginning" and "end" of the array are, so
> we can add/remove items from both ends. Also, if we start talking
> about the edge cases where we try to push on more objects then there
> is space, we either need to throw exceptions or start rotating
> objects, or whatever. What we'd end up with is some variant on a
> circular buffer, which is much more heavy weight then we really need.
I would think that all depends on how it's actually specified and
implemented. For the fixed-size stack model I described, I could easily
imagine implementing the push/pop ops with lots of copying of elements,
and no changes to any of the other operations on fixed-size arrays. For
those specific operations, performance wouldn't scale well with array
size, but nothing else would be changed.
Again, I don't have any particular point of view here. I just want to
point out that there is prior art. One can sensibly apply the notions of
push and pop to a fixed-size array.
--
Andy Dougherty [email protected]
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