[PD] note data record / playback

[Kyle Klipowicz]

Ah, so is the [pointer] object the same thing as a C pointer (*ptr)
traversing a linked list?  I knew the had the same name, but since so
many things are named strangely in Pd (right Matju?) I couldn't be
sure.

I guess the difficult thing for me with data structures is there is
only the ability to traverse and step ahead, so it seems that there
will be a lot of [until] use to get to specific portions of the data.
There is no step backwards or prepend feature, or push/pop stuff
either, which would be nice.  I guess they'd have to be abstractions?
And what would be the most efficient way to keep track of things, some
kind of construct using [until] or a counter and comparing that with
an index value in the scalar?  Arrrg.

~Kyle

On 9/12/06, Mathieu Bouchard <matju at artengine.ca> wrote:
> On Tue, 12 Sep 2006, Kyle Klipowicz wrote:
>
> > What I don't understand is why there is a completely different atom,
> > pointer, to index the datastructures.  Why not just use an integer?
> > Is it faster?
>
> This is because Miller is still using linked-lists for a bunch of things
> in Pd. Getting to element number N in a linked-list takes N steps, if you
> don't have a pointer that gives you direct access. So, yes, it's faster.
>
> I won't advocate switching to integers and B-trees or something, because
> there's also an advantage to using pointers: if you delete or insert
> elements in a list, all integers pointing to a later part of the list will
> get shifted to different elements; with pointers it's not the case.
>
> (a B-tree is one kind of array-like structure in which inserting and
> deleting is a lot faster than in regular arrays. it's made using several
> levels of nested arrays. This is not the same as a binary-tree, which also
> can be used as a fast-inserting array, but which is slower than a B-tree)
>
> (Pd could be reimplemented with a variant on the integer system in which
> integers wouldn't indicate the order of the objects, but i don't think
> that it's really worth it.)
>
>   _ _ __ ___ _____ ________ _____________ _____________________ ...
> | Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
> | Freelance Digital Arts Engineer, Montréal QC Canada
>


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