Loading a patch from plugin

computerscare · October 27, 2019, 6:29am

I would like to load a patch file from a method in my plugin. PatchManager::load seems to be the method I want, but when I call it in my code:

APP->patch->load("/Users/adammalone/Desktop/basic-patch.vcv");

I get a compile-time error: error: member access into incomplete type 'rack::PatchManager'

src/lib/routes/Rack.cpp:47:5: error: member access into incomplete type 'rack::PatchManager'
  pm->load("/Users/adammalone/Desktop/basic-patch.vcv");
    ^
../../include/app.hpp:19:8: note: forward declaration of 'rack::PatchManager'
struct PatchManager;
       ^
1 error generated.
make[1]: *** [build/src/lib/routes/Rack.cpp.o] Error 1
make: *** [plugins] Error 2

Any help would be most appreciated!

stoermelder · October 27, 2019, 6:37am

You have to include patch.hpp.

But I have to say I tried the same not so long ago and couldn’t get it working reliable. The problem is that loading a patch from a module causes synchronization issues. My best guess is that whenever you initiate a load of a patch the engine threads or the app thread are in the middle of processing a sample or frame resp. and loading will interfere with that. Sometimes it worked for me but most of the time Rack crashed. I found no way to synchronize it…

You can look at my experiments you like:

github.com

stoermelder/vcvrack-packone/blob/v1/src/Exit.cpp

#include "plugin.hpp"
#include <thread>
#include <mutex>
#include <condition_variable>
#include <patch.hpp>
#include <osdialog.h>


namespace Exit {

static std::string path;
static int workToDo;

void exit_worker() {
	if (workToDo == 2)
		APP->patch->save(APP->patch->path);
	APP->patch->load(path);
	APP->patch->path = path;
	APP->history->setSaved();
}

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Steve_Russell · March 19, 2022, 2:36am

This looks like it’s been fixed. Tried this out myself and so far it works well. It also makes the Menu Bar extension work along with importable/exportable favourites list. No need for MB module!