[PD] How's Pd limited?

Eugene Lazarchik evgenius.lazarchik at gmail.com
Wed Feb 24 10:52:26 CET 2016

Thanks for replying, Jonathan.

If Pd-l2ork starts to supports Mac I'll seriously consider switching to it.
Sounds like many of the issues and inconveniences are fixed there. Let me
reply to your questions.

> * Standard GUI objects are ugly and have limited functionality.
> Yes.  Just curious-- what's the most critical functionality you feel is
> missing?

I don't recall all of my frustrations with the GUI objects, I just remember
there were many. But let me try.
 * A button object. You know, a rectangle with a piece of text that can be
clicked to generate a bang. Usually people put a bang next to a comment,
but it takes more space. I've also seen people implementing load and save
buttons by putting "L" and "S" inside bangs. It looks really ugly and is
hard to read, especially when the bang is small. When I first saw the
browser <https://raw.githubusercontent.com/dotmmb/mmb/master/browser.mmb.pd>
abstraction from the mmb library I was very curious how it works. Turns
out, it uses sliders! They send messages when are clicked and slider
position indicator can be hidden by choosing colors in the properties menu.
I think this is a great illustration to how often PD makes us create
hacks/workarounds instead of having a nice straightforward solution.
 * Ability to remove "dented" corners (symbolbox and numberbox) and the
triangle from number2, as well as hide the border completely. They can be
helpful when doing quick prototyping but when I'm building a nice GUI, I
often don't want to see them.
 * A text box that visually indicates that it has focus and stuff is
getting entered. Even better: show a cursor, allow to move it around and
select and copy/paste text.
 * Some kind of API to determine mouse coordinates _relative to the GOP_.
Currently there seems to be no way of, say, building a menu abstraction
that will highlight menu items when mouse cursor hovers over them (it
should work regardless of how many subpatches deep it's situated and which
of the parent subpatches is currently open).
 * Drop-down list and selectbox, working out of the box, no external
 * Ability to edit subpatch/abstraction arguments from the properties menu
when subpatch/abstraction is in GOP mode with hidden arguments. Currently
one has to disable GOP, edit the arguments, reenable GOP again.
 * Ability to hide inlets/outlets when using GOP. The little boxes are
often distracting and they take additional space. Currently a similar
effect can be achieved by placing a canvas of the same size as the GOP area
that covers it.

> > * There's no good support for the concept of functions/procedures. Let's
> say we need to take some input, do some transformations and produce output,
> and we need to do that in multiple places in our patch. We can copy the
> objects but that will make the patch use more memory and there will be no
> code reuse. Another way is to make that an abstraction, but it's silly to
> make abstractions for every little thing that we need in 2 places. Also,
> instantiating 2 abstractions still uses more memory. We can try reusing the
> same code but we'll have to make multiple output connections so we'll need
> proper routing in order to figure out where to send the result. I made an
> abstraction to simplify that but this should be a standard feature of PD.
> What are the practical limitations of the higher memory use in these
> cases?  You're still going to have the same message passing overhead.

I don't know too much about how PD works internally but I imagine it
probably maps all objects into some data structure in memory and then
passes messages around by going from one object to another. The more
objects is there in the patch and all subpatches, the more memory it'll
take. It's probably a very small amount of memory per object, but
theoretically it can add up (if certain abstractions are used multiple
times in other abstractions, which are used multiple times in other
abstractions, etc.), especially on mobile platforms. Maybe the additional
memory usage is always very tiny, I don't know. But it feels weird to be

Anyway, there's other use cases for this concept. Imagine object [pd A]
that is a storage of some type. When banged on the inlet it sends the
storage contents to the outlet. Objects [B], [C] and [D] need to be able to
query the contents of object [A]'s storage. We can connect their outlets to
[A] so that they can send a bang to it but how do we route the output? We
don't want [C] and [D] to receive the output when [B] sends a bang to [A].
We can use spigots or store the output in intermediate objects ([float],
[symbol], [list]) but it all complicates the patch and makes it less
readable. I created a [func] abstraction that can be used like this:

    [inlet from B]
    [func]x[pd A]    <= A may be connected to other objects but we'll
ignore all output from it unless a message from B initiated it
    [outlet to B]

It ignores all input from the right inlet unless a message is sent to its
left inlet. In that case the message gets passed through the right outlet
to the cross-connected object. A spigot is opened on the right inlet, the
output is collected and stored (it can be multiple messages). Then spigot
gets closed and output is send through the left outlet.

I'm not sure if this is the best solution but it's the best I came up with
so far. I'm using this abstraction for my projects. I don't know how you
guys usually implement this but I think this situation is quite common.

> * *.pd format is not very friendly to Git. Try viewing diffs and
> resolving merge conflicts. Moving a subpatch on the screen causes different
> coordinates to be saved in the file, often resulting in conflicts. Cutting
> and pasting renumbers all objects and connections. This makes using
> branches and working on the same files impractical.
> Also true, but isn't the same for all dataflow/flow-based languages?

I only coded before in non-dataflow languages before so I don't know, but
it's a bummer. I tried collaborating with another person on a project and
we discovered we can't work on the same file at the same time. One thing
that could immensely help is some way of viewing the diffs. Maybe
generating a "diff" patch where differences are somehow highlighted. Or
generating a bunch of text files, one per subpatch of the main patch, and
run regular text diff on them (but try to account for object renumbering).
This sounds like a big task though, I doubt somebody implement something
like this.

> > * PD community uses mailing lists for communications, haha. In order to
> find useful information I have to view one message per page, with tons of
> distracting quotes from previous messages.
> What's the alternative?  Also, note that there is a Pure Data forum for
> general discussions, too.

The forum is great. I wish everybody used it instead of the mailing lists.

> On Sun, Feb 21, 2016 at 6:30 PM, Niklas Reppel <nik at parkellipsen.de>
> wrote:
> Hmm, i always thought that the dynamic creation and destruction of sound
> sources (oscillators etc.) pretty inconvenient in PD,
> compared to a source-code based approach.
> Maybe i missed some developments here, but the last time i checked (a year
> ago maybe), this was clearly quite
> a hassle, even though i know it's possible.
> On Mon, Feb 22, 2016 at 03:49:43AM +0200, Matti Viljamaa wrote:
> > Perhaps a bit of broad question, but I find it interesting in order to
> speculate about future additions.
> >
> > How do you think Pure Data is limited?
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