Custom Logging

By default, vm_result logs state transitions, dropped duplicate execution warnings, and unhandled exceptions to the standard Dart developer log (dart:developer) in debug mode (kDebugMode).

However, for production applications, you usually want to pipe these logs into your own central logging framework (e.g. Firebase Crashlytics, Talker, or Sentry). vm_result provides a simple, decoupled contract to do exactly this.

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1. The VMResultLogger Contract

To redirect logs, implement the VMResultLogger interface:

import 'package:vm_result/vm_result.dart';

abstract class VMResultLogger {
  void info(String message);
  void warning(String message);
  void error(String message, [StackTrace? stackTrace]);
}

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2. Registering a Custom Logger

Assign your custom logger to VMResultLogging.logger during application startup (typically in main.dart):

import 'package:flutter/material.dart';
import 'package:vm_result/vm_result.dart';

class MySimpleConsoleLogger implements VMResultLogger {
  @override
  void info(String message) {
    print('[INFO] $message');
  }

  @override
  void warning(String message) {
    print('[WARNING] ⚠️ $message');
  }

  @override
  void error(String message, [StackTrace? stackTrace]) {
    print('[ERROR] ❌ $message');
    if (stackTrace != null) {
      print(stackTrace);
    }
  }
}

void main() {
  // Register the logger before runApp
  VMResultLogging.logger = MySimpleConsoleLogger();
  
  runApp(const MyApp());
}

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3. Integrating with package:talker

If your project utilizes the popular talker library for logs and crash reporting, you can plug it in like this:

import 'package:talker/talker.dart';
import 'package:vm_result/vm_result.dart';

class VMResultTalkerLogger implements VMResultLogger {
  VMResultTalkerLogger(this.talker);
  
  final Talker talker;

  @override
  void info(String message) {
    talker.info(message);
  }

  @override
  void warning(String message) {
    talker.warning(message);
  }

  @override
  void error(String message, [StackTrace? stackTrace]) {
    talker.handle(message, stackTrace, 'VMResult Error');
  }
}

// In main.dart:
void main() {
  final talker = Talker();
  VMResultLogging.logger = VMResultTalkerLogger(talker);
  
  runApp(const MyApp());
}

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4. Default Fallback

If you don't configure a custom logger:

• In Debug Mode (kDebugMode): Standard outputs are sent to dart:developer logs (visible in DevTools and IDE consoles).
• In Profile / Release Mode: Logging functions evaluate to no-ops automatically, ensuring zero runtime overhead or leakage of logs in production builds.