I just noticed while testing that EventChannel.receiveBroadcastStream passes arguments - I'll add support for these.

A few comments below. I've never actually used the event channel API, so (especially on top of my usual lack of experience with GObject) I'm not super confident in my review here.

Have you tried finding a live use case and ensuring that you can write a Linux version of that plugin (at least, that part, with other bits stubbed out)?

I'm also a bit unsure about the correct use of the API. I've got an example program that sends a stream of integers, but I haven't found a good real-world example to implement yet.

This change is going to require the Linux template to be updated due to the new header file. But that means there must be a transition point where Flutter gets the new engine but the template is broken as it will be missing it. @stuartmorgan is there a way around that?

This change is going to require the Linux template to be updated due to the new header file. But that means there must be a transition point where Flutter gets the new engine but the template is broken as it will be missing it. @stuartmorgan is there a way around that?

What would the actual breakage be? Wouldn't the effect just be that if someone manually deleted that one specific header (and none of the others), the rule wouldn't re-run?

If it actually is broken, then it's a significant problem. Any required template update means breaking everyone's existing project. Doing that post-alpha requires going through the full breaking change process at a minimum, and ideally adding project migration logic to flutter_tool.

On the other hand if it's just that the output list won't be comprehensive for older projects, then it should be fine to just update the template and not worry about existing projects.

What would the actual breakage be? Wouldn't the effect just be that if someone manually deleted that one specific header (and none of the others), the rule wouldn't re-run?

I'm not 100% sure but I think the following might happen:

1. You create a new flutter project using Flutter before FlEventChannel was created:
   $ flutter create my_new_app
2. This app contains linux/flutter/CMakeLists.txt which refers to all the flutter_linux headers, e.g. flutter_linux.h, fl_method_codec.h etc.
3. You update Flutter, which now includes the engine that supports FlEventChannel.
4. You do flutter run -d linux, which copies the headers as specified in CMakeLists.txt. This means it wont copy the new fl_event_channel.h but will copy the version flutter_linux.h that refers to it. The program will fail to build.
5. You re-run flutter create to get the new CMakeLists.txt, the build now works.

It seems to me that CMakeLists.txt should copy all the header files found in the flutter_linux directory, though I'm not sure the best way to do that with CMake.

You do flutter run -d linux, which copies the headers as specified in CMakeLists.txt.

Ah, that's not how the copy works. flutter copies the headers (here), and the artifact that it's copying there is the entire flutter_linux folder. It doesn't care what's in CMakeLists.txt.

Tree is open now. Landing.

@robert-ancell I wonder where the method fl_event_channel_class_init is called, which initializes the fl_event_channel_dispose method? I searched the whole repository. My fear is, that I can't use the channel again, once it is disposed, but not properly. I get an error MissingPluginException(No implementation found for method listen on channel xyz.luan/audioplayers/events/somePlayerId). I may miss something, but I don't see where this method is used.
I get the error on our repository. If confirmed or disagreed, I can sent a more detailed example or search some where else. I appreciate your help :D

I wonder where the method fl_event_channel_class_init is called

See https://docs.gtk.org/gobject/concepts.html#object-instantiation

I get an error MissingPluginException(No implementation found for method listen on channel xyz.luan/audioplayers/events/somePlayerId)

That suggests that dispose has been called, not that it hasn't.

Thank you @stuartmorgan, wasn't aware of the concept.
Yeah the event channel seems to be disposed, but a new one has been created, which still is linked to the old message handler, sth like that. Need to dig deeper I guess.