[PD] Any problems else/blocksize changing subpatch blocking during dsp?

Christof Ressi christof.ressi at gmx.at
Thu Jan 16 20:03:54 CET 2020

it's certainly not a good idea to (possibly) modify the DSP graph while it's being built. As I said, the external should use a clock to schedule the message for the next tick.

> Gesendet: Donnerstag, 16. Januar 2020 um 19:07 Uhr
> Von: "Charles Z Henry" <czhenry at gmail.com>
> An: Pd-List <pd-list at lists.iem.at>
> Betreff: Re: [PD] Any problems else/blocksize changing subpatch blocking during dsp?
> On Thu, Jan 16, 2020 at 10:03 AM Christof Ressi <christof.ressi at gmx.at> wrote:
> >
> > I also think that messaging an outlet in the "dsp" method is not a good idea and it's better to use a clock with delay 0. The user might take the output of [blocksize~] and accidentally do something which interferes with DSP graph generation, e.g. by resizing an array, creating/deleting objects, etc.
> >
> > Christof
> Yes it *could*, but I'm unclear on the timing.  I've read and
> consulted the d_ugen.c code recently but .  The block parameters are
> derived from block/switch and coded into the dspcontext struct which
> gets generated for each canvas.  The parameters have to be known
> before "dsp" gets called in the current canvas (which would trigger
> the "blocksize~" output), but is the sub-patch dspcontext already
> built?  I'll try to follow up later today and try to answer it
> That ambiguity could be resolved by looking at the "bang~" code.  I
> just think it's an interesting question what is possible to happen as
> it is currently written
> bang~ sends properly timed messages by using:
> t_clock *x_clock;  //in the data structure
> x->x_clock = clock_new(x, (t_method)bang_tilde_tick); // in the "new" method
> static void bang_tilde_tick(t_bang *x)  // added "tick" method
> { outlet_bang(x->x_obj.ob_outlet); }
> and
> clock_delay(x->x_clock, 0);  // in the "perform" routine
> Chuck
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