[PD] note data record / playback

Mathieu Bouchard matju at artengine.ca
Tue Sep 12 19:09:20 CEST 2006

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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