[macOS] Launch isolate with an entrypoint from another library?

[hacker1024]

Use case

I'm trying to port the flutter_isolate plugin to macOS. On iOS, it uses the -runWithEntrypoint:libraryURI: function in FlutterEngine to launch an isolate with an entrypoint inside the plugin's Dart code - but this function doesn't seem to exist on macOS. Only -runWithEntrypoint: does, which can only launch isolates from the main library.

Futhermore, the FlutterCallbackCache and FlutterCallbackInformation classes seem to be missing, making it impossible to get information from a callback id.

Proposal

I'd like there to be a way on macOS to do what -runWithEntrypoint:libraryURI: can do on iOS.

[chipweinberger]

I'm starting to look into this.

It looks like libraryURI is used to specify which file to look for main() for the dart engine.

As a workaround, perhaps flutter_isolate can require that the function the isolate will launch into needs to be in main.dart? I'm curious if that will work.