Hi all,

I'm currently having a bit of trouble wrapping my head around the data structure stuff in PD.

I'm currently building a drum sequencer with multiple patterns and a pattern sequencer. It's currently using an 8 by 16 grid of toggles and some radio buttons but my plan is to build the "back end" in PD and then use something like pyGame to make a nicer looking interface and communicate via tcp sockets.

Incidently, this is all for running on one of these,
http://alwaysinnovating.com/home/index.htm
It took a bit of persuasion but it seems to run fine.

Anyway, the crux of the problem im having is basically just understanding how i can deal with multiple structs. I have a patch that has a struct and a data window, there are 8 toggle rows which each correspond to a float in the struct and i have a system that can store and recall 8 patterns. The pattern sequencer works and i have everything working so that i can step through sequenced patterns nicely and get the toggle button states coming out. All good so far.

My only real issue is that this is just one track and i'd like multiple tracks, but i dont really get how i could go about making an abstraction that contains a struct and a data window i can write to but without having things interfere with each other. I realise that data windows need to be unique, but what about templates and the structs themselves?

any help on this would be much appreciated, I'll try to post up my patch when i get a chance later this evening

Structs must be outside the abstraction. In the sequencer I'm building, my data windows are named [pd $1-window] within a [track] abstraction, which first argument is the number of the track :
[track 1], [track 2]...

Structures have to be declared only once, otherwise you get errors. So the unique shared templates and structs are in a subpatch, in the same patch as the [tracks].

This way you can handle separately the different data windows corresponding to different tracks, as whithin [track 1] the data window is called "pd-1-window".

ok, a few other questions just to clarify things.

So i could go about doing things by having a struct called track_info, in a template subpatch which is sitting in my mainpatch. I then have an abstraction which contains the data window subpatch and uses $1 to make each of them unique.

within this abstraction, all the traverse objects would be pointing to the template, but any get/set/append objects would be using $1 arguments themselves to point to the data window in the abstraction.

Sorry if any of this should seem obvious, i'm just being a little slow to wrap my head around how structs, templates and data windows fit into the whole affair

Right, but there's a trick with abstractions, arguments and messages I forgot to mention:

[traverse pd-$1-window, bang(
|
[pointer, append, set, get, etc...

won't work within the abstraction because in a message, $1 is an inlet not an abstraction argument. Funny, isn't it ? Instead, use :

[float $1]
|
[traverse pd-$1-window(
|
...
to feed the message with the right creation argument.

You can also manage all datastructures from the main patch by feeding [traverse pd-$1-window, ...( with the number of the track you selected.

ah ha ok, im understanding this alot more now.

This evening Ill have a go at getting a track abstraction working properlly and i'll report back with success/failure.

I think i'm also going to try and change from using floats in the structs to using arrays. depends how much i manage to get done.

many thanks for all the help. hopefully ill be sharing something useful later this evening

hey, just wanted to say thanks for the help, ive got everything working great now. Just in the middle of abstracting things into a full sorted patch and making it ready for using OSC messages.

I'd like to post if up some place for people to look at but i think i'll wait and tweak it some first

anyone who can use data structures well is a true hero.

most people (like myself) give up after they have torn the last hair from their head in frustration.

you're welcome, glad to see you succeded, you hero

clearly i need a cape now

truth be told im not sure im using them well, just using them heh. The stuff in the documentation with the graphical stuf and using drawable canvases to control stuff....that still confuses me.

i might try and learn it for giggles at some point but right now i just want a sequencer that helps make techno.

I've attached what i've done so anybody interested can have a look at it. the next thing i'll be doing is changing the struct to use arrays to contain the track data instead of lists. just seems neater to me.

I've also been setting things up so that it should be easy to change over to using OSC when i get round to doing it

any advice/criticism/ideas for super hero name welcome

http://www.pdpatchrepo.info/hurleur/drum_sequencer.rar