method_call_dispatcher 0.3.0

A scaffold for writing flutter plugins

Flutter MethodCallDispatcher

Tired of endless switch-cases in your Flutter plugin code? This module is for you!

(kotlin only, swift coming soon!)

TLDR

It lets you turn this:-

channel.setMethodCallHandler { call, result ->
  when (call.method) {
    "orange" -> ...
    "banana" -> ...
    "mango" -> ...
    "apple" -> ...
    .
    .
    .
  }
}

Into this beauty:-

import com.pycampers.method_call_dispatcher.MethodCallDispatcher


class MyPlugin : MethodCallDispatcher() {
    fun orange(call: MethodCall, result: Result) {
        ...
    }

    fun banana(call: MethodCall, result: Result) {
        ...
    }

    fun mango(call: MethodCall, result: Result) {
        ...
    }
    
    fun apple(call: MethodCall, result: Result) {
        ...
    }
      
    .
    .
    .
}

channel.setMethodCallHandler(MyPlugin())

Errors

Any errors that occur in native code tend to instantly crash the app. Sending them back to flutter can be a real PITA.

This module does everything in its power to prevent such mishaps.

import com.pycampers.method_call_dispatcher.MethodCallDispatcher
import com.pycampers.method_call_dispatcher.trySend


class MyPlugin : MethodCallDispatcher() {
    fun myBrokenMethod(call: MethodCall, result: MethodChannel.Result) {
        // This won't crash the app!
        // The exception will be serialized to flutter, and is catch-able in flutter.
        throw IllegalArgumentException("Hello from Kotlin!")
    }

    fun myBrokenCallbackMethod(call: MethodCall, result: MethodChannel.Result) {
        // Automatic exception handling can only work in non-callback, synchronous contexts.
        //
        // So, trySend guarantees that app won't crash,
        // and errors will be serialized to flutter,
        // even in a callback context.
        java.util.Timer().schedule(
            object : java.util.TimerTask() {
                override fun run() {
                    trySend(result) {
                        throw IllegalArgumentException("Hello from Kotlin!")
                    }
                }
            },
            1000
        )
    }
}

And yes, You get 100% dart catch-able PlatformExceptions with stacktraces of native code!

D/MethodCallDispatcher( 3572): piping exception to flutter: java.lang.IllegalArgumentException: Hello from Kotlin!
E/flutter ( 3572): [ERROR:flutter/lib/ui/ui_dart_state.cc(148)] Unhandled Exception: PlatformException(java.lang.IllegalArgumentException, Hello from Kotlin!, java.lang.IllegalArgumentException: Hello from Kotlin!
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1$run$1.invoke(MainActivity.kt:33)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1$run$1.invoke(MainActivity.kt:30)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher.MethodCallDispatcherPluginKt.trySend(MethodCallDispatcherPlugin.kt:52)
E/flutter ( 3572): 	at com.pycampers.method_call_dispatcher_example.MyPlugin$myBrokenCallbackMethod$1.run(MainActivity.kt:32)
E/flutter ( 3572): 	at java.util.Timer$TimerImpl.run(Timer.java:284)
E/flutter ( 3572): )

Example app

See the example app available @ main.dart & MainActivity.kt

Installation is same as for any other flutter plugin, except that this one doesn't have any dart code :-)

The core plugin code can be found at MethodCallDispatcherPlugin.kt