(Side note: editor: true is the default and therefore redundant.)
You can see this pattern a few times in the docs.
~pt.open("Pianoteq 8.so", editor: true);
s.sync; // must wait for plugin to load
Don’t use s.sync, use an action function! The documentation explicit says:
NOTE: You must not use Server: -sync to wait for completion! If you prefer to write sequential code instead of callbacks, you may use a Condition resp. CondVar and signal it from the action function.
So the correct solution would be the following:
fork {
SynthDef(\mysdef, { |out = 0| Out.ar(0, VSTPlugin.ar(numOut: 2)); }).add;
s.sync; // must wait for synthdef to be ready
~pt = VSTPluginController(Synth(\mysdef));
~pt.open("Pianoteq 8.so", action: { |x| x.program_(26) });
}
Or as a one-liner:
fork {
SynthDef(\mysdef, { |out = 0| Out.ar(0, VSTPlugin.ar(numOut: 2)); }).add;
s.sync; // must wait for synthdef to be ready
~pt = VSTPluginController(Synth(\mysdef)).open("Pianoteq 8.so", action: { |x| x.program_(26) });
}
Not true! See my post above. TBH, I find it a bit frustrating that people would assume that I wouldn’t provide such basic functionality… When in doubt, read the docs!
The work around is to set an explicit wait time before opening the editor
No, just no!
there might be a more elegant way to this, if it exist I would be keen to know
See above
Writing docs is hard… On the one hand, I think the documentation for VSTPlugin is quite extensive, but I also get that it can be a bit overwhelming and most people just don’t read it. I guess I need to revise the “Introduction” section to include the use of the action function. Now, if people wouldn’t even read that, I’ll just give up
Generally, suggestions for improving the documentation are very welcome. It can be hard as an author, who knows the software inside out, to write good documentation for beginners.
No need for the aggression, I stand corrected and I did read the docs several times but either forgot or missed this case. And btw, I am very happy about the VSTPlugin and use it extensively, thanks for the hard work.
No aggression, just frustration. And not about you in particular, but about writing docs in general. Sorry if I was a bit harsh.
As I said, the mistake is on me, I should already show this usage in the introduction and not bury it deep down in the method documentation… When even a power user like @jamshark70 gets the usage wrong, the problem is really on my end.
And btw, I am very happy about the VSTPlugin and use it extensively, thanks for the hard work.
Thanks for the kind words! I’m glad people find it useful.
Every one of these lines (except the VSTPluginController line) is an asynchronous operation.
Aha, I was not aware of that. So is it just an accident (because you are much slower that way) that it works when you run the lines individually or does the ide insert implicit syncs?
What now remains unclear to me is why you ever would want to run “open” without supplying an action as then you never really know when the plugin is ready and everything becomes a timing lottery.
So a less user-error-prone interface could be that you either supply an action or if you don’t do that open only returns when the plugin is ready to use. Or is there a use-case for initiating the loading of a plugin and not caring about when it is ready?
Finally what is the use-case for “open” with “editor: false”? Does that make the loading of the plugin more efficient when you are sure you never want to use the editor?
The former. As I already said above, I should probably change the documentation and use proper action functions instead of line-per-line style even in the introduction.
So a less user-error-prone interface could be that you either supply an action or if you don’t do that open only returns when the plugin is ready to use.
I’ve followed the general pattern of the SC Class Library which is to provide action functions. See, for example, Buffer.read.
At least with Buffer.read you can just use s.sync instead (which is problematic for a bunch of other reasons), but with VSTPluginController.open this is not a (reliable) option because the method might take more than one Server roundtrip.
Personally, I would have preferred it if async methods would return a Promise object, like in JS, ideally with a nice async/await syntax, but the SC Class Library has been designed long before async programming became mainstream, so at the moment we are stuck with callback hell
Finally what is the use-case for “open” with “editor: false”? Does that make the loading of the plugin more efficient when you are sure you never want to use the editor?
Exactly.
Or is there a use-case for initiating the loading of a plugin and not caring about when it is ready?
I can think of at least two use cases:
you are happy with the default settings of the plugin
BTW, you can always “convert” callbacks into sequential style with the help of CondVar:
fork {
var cv = CondVar();
~fx = VSTPluginController(~synth).open("foo", action: { cv.signalOne });
cv.wait { ~fx.isOpen }; // note the boolean test!
// now you can use the plugin
~fx.editor;
~fx.loadPreset("baz");
}
You should add a cookbook-section to the documentation on how to do typical use cases properly.
In an experimentation-friendly enviroment like sc people only read documentation when something goes wrong and there is a lot of cargo-cult programming where you copy some snippet from somewhere that seems to work and so you assume that this is the way to do it when in reality it is just a hack that works for reasons you don’t even understand.
But the more I understand about the problem the more I come to appreciate that the interface is actually quite well thought out.
Actually, VSTPluginController.schelp has a bunch of examples for typical use cases at the end.
The second sentence of the help file literally says:
Have a look at the examples at the bottom!
I guess I should add a link to the section… It would stick out visually and also make it easier to navigate.
In an experimentation-friendly enviroment like sc people only read documentation when something goes wrong and there is a lot of cargo-cult programming where you copy some snippet from somewhere that seems to work and so you assume that this is the way to do it when in reality it is just a hack that works for reasons you don’t even understand.
So what happens if the open fails in the above example with the CondVar?
Does cv,wait then block forever?
I was afraid you would ask this Yes, in this case it would block forever. (Note that you would still get an error message in the console, so you at least know that something has been going wrong.)
Here’s the version with error handling:
fork {
var cv = CondVar(), done = false;
~fx = VSTPluginController(~synth).open("foo", action: { done = true; cv.signalOne });
cv.wait { done }; // note the boolean test!
if (~fx.isOpen) {
// now you can use the plugin
~fx.editor;
~fx.loadPreset("baz");
} {
// error handling
}
}
Or with the older Condition (which does not require to check a separate variable):
fork {
var cond = Condition(true);
~fx = VSTPluginController(~synth).open("foo", action: { cond.signal });
cond.wait;
if (~fx.isOpen) {
// now you can use the plugin
~fx.editor;
~fx.loadPreset("baz");
} {
// error handling
}
}
Is ~fx still useful in the error handling branch (maybe to get more details on the error condition) or is at this point all you know that the open was not successful and ~fx can no longer be used?
You wouldn’t get any details, no. The reason for the failure is posted to the console though.
and ~fx can no longer be used?
You can try another plugin
I have to admit that I personally don’t really do any error handling when opening plugins. It’s not like plugins will just refuse to open randomly. Once the plugin has been probed successfully, I can just assume it will always work. If something goes wrong for some unexpected reason, the console will tell me anyway.
Could be that you can’t initialize the Condition with true and instead set test to true in the action function. TBH, I always forget how Condition works…
Personally I tend to use CondVar because the semantics are more clear to me. Just don’t forget the boolean check in the call to wait!
I have tried to do away with the boolean check in wait as I don’t understand why it is needed - but it definitely seems to be necessary - can you explain why that is?
So why is it not sufficient to have the action signal the condvar which should wake up the thread sitting on wait (without a predicate) which can then check if the plugin is open. But when I try it like that it seems wait block forever - but why is that?
You are talking about CondVar and not Condition, right? Classic condition variables always need a predicate because they do not ‘know’ that they have been signalled. If the async operation is very fast, the callback may be scheduled before the main routine calls wait. In this case, signalOne has no effect because the routine isn’t waiting yet. Without the predicate, the subsequent wait call would block forever because nobody will signal it. With the predicate, it will just return immediately without waiting.
Yeah, that’s how Condition is supposed to be used. I got a bit confused there.
